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These pages represent a biased choice of dates relevant to biology, obtained by compiling a great many different sources, often using the original texts and not the WWW; the information collected here does not use Wikipedia which, by construction, relies on a process akin to a vote, and changes over time in order to reflect some kind of a popular anonymous consensus about knowledge. Care has been taken to check information and rewrite it when needed; direct access links to the original sources is provided whenever possible; however date records still contain many errors; the links are chosen to be as diverse as possible, they do not engage the responsability of the author. Note however that many WWW links are generally unstable, so that many might be obsolete despite regular checks.

Note that the links in French and in English may differ. Notez que les liens en Français et en Anglais sont souvent différents.

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Back in time, and in civilisations other than the one located in Greece, it is difficult to collect appropriate information about what science, and especially biology was. Astronomy and Medicine were practiced everywhere in the world, associated to religious or ethical behaviour and practices. It is therefore impossible to draw a specific line between what became science and what were other social practices. The choice presented here is therefore the more biased the more we go back in time. And we shall certainly amend our presentation as time elapses. This page is therefore to be considered as under permanent (re)construction. It is however quite certain that Science had something to do with the transformation of Myths and Epics into a formalized representation of the world. The people lacking such organized view of their origins would not, therefore, easily accept science when it came and were not prone to develop it.

It is most likely that modern Homo sapiens born 200,000 thousand years ago, somewhere in Eastern (Central) Africa, came out of that continent, through Ethiopia and Southern Egypt, then to Mesopotamia, while migrating eastward at the rather fast speed of about fourty kilometers per century. Western Asia was invaded first, with a very old human branch going southwards as far as Australia at a time when glaciations lowered considerably the Ocean level. It seems now likely that there has been several waves of migration, with local speciation and mixing. It now seems that Homo sapiens sapiens mated with Homo sapiens neanderthalensis, giving birth to Caucasians and Asians, and a second time with Homo sapiens neanderthalensis Denisova, to give birth to Melanesians. Appropriate selective mutations, in particular of the skin's pigmentation, hair production and nose shape had to appear to create human types more adapted to the local environmental conditions. In particular a light skin complexion was probably needed to catch more sun light, and thus prevent rachitism when Man migrated northward. In the same way, body hair, which had disappeared earlier, perhaps as a beneficial trait against body parasites, sometimes reappeared with the selection pressure imposed by low temperature in northern parts of the world. The neolithic revolution appeared subsequently some 12,000 years ago. The earliest home of human written civilisation is now generally supposed to have been Sumer, with another root in Egypt shortly after the Neolithic revolution began. The Chinese written civilisation goes way back in time (several thousand years after Sumer and Egypt however, consistent with the usual speed of human migration), and there are most probably links between the former and the latter, through the West-East link which had to go through the mountains of what is now Afghanistan and the Xinjiang desert towards the centre of China. In fact in more recent times this route was followed by Alexander the Great (356-323 BC), and there remains valleys in Afghanistan where people still speak a Greek dialect.

In Egypt, was very early on (starting some 6,000 years ago at least) developed an art of healing which was certainly based not merely on superstition (and in particular on superstition associated to natural numbers, small integers) but also upon actual observation. Despite its extreme importance for the creation of knowledge, the contribution of ancient Egypt has usually been overlooked. Many reasons may account for this, but it is most likely the development of the three major monotheistic religions which played the most significant role in what must be considered as a blind spot or even as a purposedly organized censorship of the Egyptian thought. One can indeed trace back in history many of the actual texts found in the hebraïc Bible (and subsequent christian and islamic derivatives) in Egyptian beliefs and texts. And of course, religions which state that God reavealed Himself through talking to prophets can hardly accept that the content of God's revelation can be deeply rooted in history... Pharao Amenophis IV, who made himself known as Akhenaton (~1380 - 1337 BC), created a remarkable monotheistic religion which is likely to be concomitant with and probably predates Moses travels and sayings. But neither the Israelite Hebrews, who had to fly away from Egypt, taking the new religion with them (they would fuse it with the other manichean, babylonian creeds when in Palestine, hence the two tales of Genesis in the first part of the Bible), nor the Christians, nor, finally, the Muslims which now occupy Egypt (the Christian Copts are probably much nearer the Truth of their fathers than any other religion) could easily accept that their beliefs have a concrete, factual, history. High level theologies accept this type of situation, but their teaching is not spread as a common cultural background... And it goes without saying that because a significant part of Egypt was of black complexion and clearly descending from central Africa, there was and still is a strong reluctance to accept that major human advances could have come from people with a black skin. The same is true when we witness the interesting resistance of many people (especially in Asia) to accept that modern Man is an ... African.

Sumerians, Egyptians, Babylonians, followed by Indians and Chinese succeeded in collecting a considerable mass of individual facts, sometimes extremely astute, which were organised along the local religious or ethical creeds. Then, about 2,500 years ago, with the creation of the Presocratic philosophy in Greece, science was born, with an entirely new and original way to organise human knowledge.

It is very important to be able to distinguish between religion and philosophy. Philosophy has many meanings, but it contains one central point: it is thinking about thinking. Religion is mostly organized around a reflection about Life and above all, Death, and it is associated to practices involving the behaviour of Man facing Death, the only hard fact everyone has to face. This explains why there may be certain contradictions when people mix up Philosophy and Religion. For example, in China, Daoism can be either a Philosophy, or a Religion. As a Philosophy (dao jia 道 家), the Dao, the Way, encourages people to follow Nature, as a Religion (dao jiao 道教), it is a set of practices against Nature, trying to avoid Death. Of course a philosophy is underlying any type of religion, but a religion implies a social structure, rites and beliefs organised in a socio-political way. Similarly, philosophy is concerned by the question of life and death, but, by construction, philosophy questions the world (including beliefs), while religion, with its social structure and rites, answers questions, from all eternity.

Science, the daughter and extension of philosophy, is organized exploration. That it has been created by Greek philosophers, travelling from island to island, from Western Asia to Sicily, is no chance. It is not the place here to discuss geographic, economic and socio-political reasons underlying the birth of Science, but the quasi-absence of China from the scene is no chance despite its extremely old and involved aptitude in developing new techniques. Probably through interactions with the Greek world, science certainly started to develop in China and India (this can be seen in old mathematics treaties). However, China, geographically, politically, and economically emphasizes stability, not questioning or exchanging. This explains why science was uprooted there when it became to be visible. The main social categories in China (scholars, farmers, artisans, merchants, in that order of importance, the first three, associated to production, making "the root" and the last, associated to exchange, "the branch") account for the sharp distinction between what is of nature and what is of man, what is natural and what is artificial, a distinction which is relevant to today's reactions about genetically modified organisms, for example.

This being said, we can find dates where scientific facts, questions and hypotheses were put forward and slowly organised to yield present day science. We are interested here in biology, which is science associated to agriculture and medicine. But since science also means development of reasoning and development of an experimental approach, the first dates with which we shall be concerned will correspond to the creation of logics and the creation of the first experiments.

Science needs stable transmission of knowledge. This requires something more practical and less error prone than oral transmission. We need therefore to retain as major dates those in which writing was invented, then writing on supports that were easy to construct: stone, clay tablets, papyrus and paper (later on, the skin of animals). One must be very careful when interpreting later reconstructions of ancient history: only actual texts and pictures in monuments and other artefacts, which can be dated precisely, can give a reliable evaluation of dates of inventions. It must be borne in mind that all civilisations tend to self-appropriate the origin of discoveries to their own people, without much control, and in fact, it seems clear that the origin of most important early discoveries were made in civilisations no longer extant, the Sumerian and Egyptian civilisations. It must also be borne in mind that Man was always mobile, with a speed of invasion rather fast: well over one hundred kilometers per century after the beginning of the Neolithic age, because of the help provided by the domestication of animals, and the possibility to bring seeds to provide food support. Hence many discoveries traveled back and forth during the first millenia of the Neolithic age in a way which is still very poorly documented.

~10000 BC The dog is domesticated in Mesopotamia. The taming of animals and the cultivation of plants begins to spread both eastwards and westwards at the speed of about 50-100 km per century.

~6000 BC Yeast is used by Sumerians to make beer and wine. This practice slowly diffuses southwards, eastwards and westwards. Process metallurgy begins as one of the oldest sciences with the processing of gold.

~5000 BC The first cities are created in Mesopotamia. The horse is domesticated in Ukraine. From this date onwards diffusion of human knowledge becomes much faster, with the spread of horses as a means of transport and communication.

~4200 BC Copper is discovered as a metal susceptible to processing. It remains a symbol of the beginning of civilisation in the middle East, and its name is associated to this region (the symbol for copper is Cu and comes from the latin cuprum, meaning from the island of Cyprus).

~4000 BC The Egyptians discover how to bake leavened bread using yeast. Donkeys are domesticated. Communication spreads fast along the Nile river benefiting from the opposition between the stream of the Nile (which goes North) and the dominant wind (going South). The Sumerians and the Egyptians discover silver processing.

~3600 BC Copper alloys are used by Egyptians and Sumerians. The first copper smelted artifacts are found in the Nile valley: copper rings, bracelets, chisels; smelting of gold and silver are known. Exchange with Africa through the Nile valley brings minerals and metals to Egypt.

~3500 BC The Egyptians begin to write down accounts of important royal events, first on stones, then on wood. The Egyptians use galena (lead sulfides with a metallic shine) as cosmetic for blackening features of the face.

~3400 BC The first symbols for numbers, simple straight lines, corresponding to a decimal number counting system (without the zero) appear to be in use in Egypt. The Egyptian know how to extract the metal from copper ore.

~3300 BC Sumerian writing on clay tablets becomes a common practice. The Minoan civilisation begins in Crete, pervading all the Aegean sea.

~3250 BC The wheel is in use in Mesopotamia .

~3000 BC Tooth filling is performed in Sumer. The Sumerian writing evolves into cuneiform. The abacus is developed in the Middle East and in areas around the Mediterranean. Hieroglyphic numerals are in use in Egypt.

~3000 BC to 2500 BC Sumerian medicine discovers the healing qualities of mineral springs. The weaving loom is known in Europe.

~2800 BC Beginning of systematic astronomical observations in Egypt, Babylonia, India, and China. Egypt introduces a calendar of 365 days without adjustments.

~2750 BC The great wall of Uruk, with 900 towers, is built in Mesopotamia. The construction of Cheops Pyramid conforms in layout and dimensions to astronomical measurements. Sumerians begin to use a sexagesimal number system for recording financial transactions. It is a place-value system without a zero place value. This is the probable date of manufacture of the first iron objects, but iron smelting is not yet practical. Iron processing will be exported to the East and North-West following human migrations, while being continuously improved.

~2500 BC Egyptian carvings depict existing techniques of surgery. In Egypt, papyrus, the first attempt to use a convenient light support for writing, becomes a common support. Another way to make vegetal paper was rediscovered in China, with a more elaborate process, several thousand years later and subsequently exported to Europe. Beginning of the historical record of the Chinese civilisation.

~2100 BC The earliest known legal texts are written by Ur-Nammu, king of Ur.

~2000 BC In Egypt, the ratio between the radius of a circle and its circonference is measured as 3. This is later on transmitted to the Hebrews and to the Greeks. The Egyptians introduce a form of contraceptive. Egyptians use knotted rope triangle with whole numbers (a² + b² = c²: "Pythagoras" theorem) to construct right angles. Harappans adopt a uniform decimal system of weights and measures.

~1900 BC A papyrus written in Egypt (The Moscow papyrus, also called the Golenishev papyrus) gives details of Egyptian geometry. Four basic elements are known in India to describe material objects: Earth, Air, Fire, and Water. The original place of this description is not known (it could be as far away as Egypt). It becomes the rational basis of the description of all forms of matter throughout the Middle East for several millenia.

~1800 BC Babylonians use multiplication tables.

~1750 BC In Crete, Minos palace has light and air shafts, bathrooms with water supply. Irrigation system in Egypt systematically utilizes Nile floods. The Code of Hammurabi (who founds Babylonia) includes guidelines for medical practices (including eye surgery) and permissible fees. Babylonia uses highly developed geometry as basis for astronomic measurements and creates the signs of the zodiac. Tin is discovered and added to copper in metal alloys. The Babylonians solve linear and quadratic algebraic equations, compile tables of square and cube roots. They use Pythagoras' theorem and use mathematics to extend knowledge of astronomy.

~1700 BC The Rhind papyrus (sometimes called the Ahmes papyrus) is written. It shows that Egyptian mathematics has developed many techniques to solve problems. Multiplication is based on repeated doubling, and division uses successive halving.

~1600 BC A decimal system appears to have been in use in Crete (or, most likely, introduced from Egypt). The highly evolved Minoan civilisation flourishes until it is destroyed, perhaps after the explosion of the volcano in Santorini which covered most of the region with ashes and sterilized everything for more than a century. Mercury (Greek- ὑδραργυρος, liquid silver; latin- argentum vivum, live or quick silver) is stated to have been found in Egyptian tombs of this time.

~1550-1200 BC The Minoan civilisation develops its own writing system. The Linear A script was a basis for the development of the Linear B writing, which emerged here on Crete in about 1450 BC and soon spread to continental Greece. Both Linear B and Linear A were written during the 2nd millennium BC in Minoan Crete. Michael Ventris deciphered Linear B in 1952. This is the written syllabic language that spread from the Minoans to the Myceneans. Linear A has not yet been deciphered. The influence of this civilisation in Greece in terms of Science is therefore still unknown.

~1500 BC The practice of iron smelting becomes common in Syria and Palestine. During the Shang 商朝 period (1700 BC-1027 BC) appear the first Chinese pictograms engraved on bones. Medicinal bloodletting has been practiced since the Stone Age. Almost every ancient and modern culture has drawn blood to cure disease. Early cultures believed that illness was caused by evil spirits and that these could be removed by withdrawing blood from the patient. A way to control blood letting is to use animals: the earliest known illustration of the use of leeches for medicinal purposes is a painting in an Egyptian tomb. The sundial is used in Egypt to measure the time of day by the sun's shadow. Hours are shorter in winter and longer in summer.

~1400 BC An intricate clock, measuring flow of water, deposited in the tomb of Amenophis III demonstrates domination of first experimental science by Egyptians. The remains of glass furnaces discovered by Flinders-Petrie at Tel-El-Amarna in Egypt illustrate the manufacture of rods, beads, and jars or other figures, formed apparently by covering clay cores with glass and later removing the cores.

~1300 BC Mathematical permutations and "magic squares" are known of Chinese mathematicians. A decimal number system with no zero starts to be used in China. The properties of the Pythagorean triangle become known. Using these properties the height of sun in relation to the incline of polar axis is measured in China.

~1100 BC First proven domestication of the silkworm in China (said to have existed well before that date, but not proven, sure to have existed after 500 BC). Advanced knowledge of shipbuilding is developed in Mediterranean and Scandinavian countries, with concomitant exploration of far regions of the World by sea. The Egyptians make models of Anubis, one of the Gods of Deads, with a mobile jaw, meant to simulate speech. These are the first ancestors of modern robots simulating life.

~1000 BC Chinese use counting boards (abacus) for calculation.

~950 BC "Biotechnology" extends away from the simple agro-food processes or from medicine: fabric dyes are made from purple snails and staining with alum practiced in Mediterranean area. The Indian lunar year has 360 days adjusted at random to coincide with solar year. A Chinese textbook of mathematics includes planimetry, proportions, "rule of 3" arithmetic, root multiplication, geometry, equations with one and more unknown quantities, and a theory of motion. Earliest use of iron smelting in Greece. Chaldeans use water-filled cube for measuring time, weight, and length.

841 BC Beginning of the verified Chinese historical chronology.

~800 BC Baudhayana is the author of one of the earliest of the Indian Sulbasutras (texts about mathematical problems). The Chinese begin to use iron, after smelting is slowly introduced from the West. Medicine becomes divorced from priesthood and medical training in India uses anatomical models. In Greece, Homer refers to highly developed battlefield surgery. Sledges with rollers are in use for heavy loads. Assyrians use animal bladders as swimming aids in warfare.

763 BC King Adadnirari 11 of Assyria starts a new chronology (verified in connection with solar eclipse of June 15 of that year).

~750 BC Manava writes a Sulbasutra. Manava's Sulbasutra, like all the Sulbasutras, contains approximate constructions of circles from rectangles, and squares from circles, which can be thought of as giving approximate values of π. There appear therefore different values of π throughout the Sulbasutra, essentially every construction involving circles leads to a different such approximation. An interpretation of verses 11.14 and 11.15 of Manava's work gives π = 25/8 = 3.125. Babylonian and Chinese astronomy understands planetary movements; the Babylonian new calendar is confirmed. Spoked wheels and horseshoes are in use in Europe.

~650 BC King Assurbanipal's famous library, with over 22,000 clay tablets, covers history, medicine, astronomy, astrology. The movement of planets and signs of zodiac are recorded in Assyria, where water clocks are constrructed. King Sermacherib's garden in Nineveh palace has rare plants and animals; planting space and irrigation channels are blasted from rock, allowing improvement in plant breeding and a beginning of hygiene. Progress in water installations; Jerusalem has subterranean water tunnels; Sermacherib builds an aqueduct; Nineveh has bucket wells. Kaleos is the first to sail through the Straits of Gibraltar (Pillars of Hercules). Glaucos of Chios invents the soldering of iron. Pharaoh Nechos of Egypt (reigned 609-593) starts a canal between the Nile and the Red Sea. He also orders the first reliably recorded circumnavigation of Africa by Phoenicians.

~600 BC Apastamba writes the most interesting Indian Sulbasutra from a mathematical point of view. In India, our present decimal-positional method of writing numbers originates. It took a long time for this mathematical system to make its way to the Mediterranean/European area and to be accepted. It took an even longer time to be accepted in China. Witnessing the archaic system still used for measuring weight and distances in America today, it is easily understood that very primitive ideas can have a long life. The decimal system became common after the Islamic arithmetic was developed.

~590 BC Thales (Milet, 625 - 547) choses the Ocean as the primitive element. He knows that a magnet attracts iron and that amber, when rubbed, becomes magnetic. He brings Babylonian mathematical knowledge to Greece. He uses geometry to solve problems such as calculating the height of pyramids and the distance of ships from the shore. The "Thales Proposition" (triangles over the diameter of a circle are right-angled) is oldest theory of occidental mathematics. A water system is built by Eupalinos, on the island of Samos, a three-quarter-mile-long tunnel started simultaneously at both ends. Priscus builds the first Roman stone bridge. Nebuchadnezzar 11 builds a palace with terrace gardens in Babylon (presumed to be the legendary "Hanging Gardens," one of seven wonders of the world); a tunnel more than half a mile long, connecting the palace and the Temple of the Sun, traverses the Euphrates below the river bed. Theodoros of Samos is credited with invention of iron casting, water level, lock and key, carpenter's square, and shaping clay by wheeling. The Roman lunar year has 10 months of varying lengths (later 12 months). Babylonian astronomy begins to conform to present reckonings; the lunar year has 354 days regulated into 12 months alternating between 29 and 30 days.

~580 BC Anaximander (Milet, 611 - 547) choses the illimited (Απειρον) as the primitive element. He also draws the first map (on papyrus). He is credited with the first written work on natural science, a classical poem entitled Περι φυσεως (On Nature). In this poem, he states that human beings must descend from aquatic animals, presenting what may be the first written theory of evolution, stating that in the beginning there was a fish-like creature with scales that arose in and lived in the world ocean. As some of these advanced, they moved onto land, shed their scaly coverings, and became the first humans.

~550 BC Anaximenes (Milet, 585 - 528) emphasizes the processes of condensation and rarefaction needed to create all extant forms, including living organisms.

~540 BC Sushrata teaches medicine at the University of Benares about surgery, obstetrics, diet, bathing, drugs, infant feeding and hygiene, and medical education.

~540 BC Xenophanes (Colophon, 570 - 475) can be said to have been the first to formalize the hypothetical nature of what we now know as Science, differentiating between the World and its truth (αληθεια) and Models of the World (δοξα). Xenophanes is one of the first people to write about his observations of fossils, thinking that fossils were an indication that there was water/mud previously in an area. Counting rods are used in China.

~530 BC Pythagoras (Samos, 560 - ~480) moves to Crotone in southern Italy and teaches mathematics, geometry, music, and reincarnation. His world is based of the organisation of Monads: the integers. A link is made between the alphabet and the whole numbers. In fact this is what prevented the discovery of the concept of zero, discovered later in India. Zeno (Elee ~570 - ?) emphasizes the question posed by the contradiction between the continuous and the discontinuous.

~510 BC Heraclitus (Ephese 540 - 475) places emphasis on Change as the principal cause of things.

~500 BC Human cadavers are dissected for scientific study by the Greek physician Alcmaeon (Crotone, 535 - ?) who discovers what we know name the Eustachian tubes in the ear. He states that good health results between the equilibirum of powers similar to those described by Anaximenes 'humidity/dryness' 'cold/heat' 'bitterness and sweetness', while disequilibrium causes diseases. He also discovers the difference between veins and arteries, as well as the connection between brain and sensory organs. In India, Panini's work on Sanskrit grammar is the forerunner of the modern formal language theory. The first known cataract operation is performed by Sushrata in India (Susrata Samhita). The Babylonian sexagesimal number system is used by the astronomer Naburiannuto to record and predict the positions of the Sun, the Moon and the planets. Hanno the Carthaginian travels down the western coast of Africa. Hecataeos (549 - 486) mentions India in his writings, proving that the exchange between Far East and Greece was already significant. Development of technology and agriculture in China. Confucius (Kong Fu Zi) (551-479) teaches general rules of behaviour that are still followed in China in many places. As Socrates or Jesus Christ he does not directly write, and his sayings are recorded by followers. Emphasis is not placed on knowledge itself as a goal, but, in contrast, on knowledge of moral rules (in particular family values).

494 BC Destruction of Miletus by the Persians.

~490 BC Parmenides (Elea ~515 - ?) in contrast to Heraclitus places emphasis on Permanence.

461-456 BC The wall from Athens to the Piraeus is constructed.

~450 BC Empedocles (Agrigente, 492-432) choses the four elements (Earth, Water, Air and Fire) and their combination as making all things. His view of the creation of living forms is strikingly similar to the views much later held by selective theories derived from Darwin's thought. He also emphasizes the combinatorial nature of living forms. Before this time, the Greeks disputed which one(s) of four possibilities were the “original”elements: some said one, some said another, some said two together. Empedocles said he thought there were four original elements: Earth, Air, Fire, and Water. He thought that everything else come about through their combination and/or separation by the two opposite principles of Attraction and Repulsion. Leucippus (Abdere ~490 - ?) proposes that things are made of Atoms, unbreakable structures which can combine together in an infinite way "No Thing comes to being by itself, but everything is derives from a Law (Λογος) and is under the constraint of Necessity" Diogenes of Apollonia (Apollonia, Phrygia or Crete? 499/98 - 428/27) writes his Περι φυσεως in an eclectic fashion, agreeing in some points with Anaxagoras and in others with Leucippus. Like Anaximenes, he says that the primary substance of the universe is Air infinite and eternal, from which by condensation, rarefaction, and change of state, the form of everything else arises. Like Anaximander, Diogenes regards the sea as the remainder of the original moist state, which has been partially evaporated by the sun, so as to separate out the remaining earth. The earth itself is round, that is to say, it is a disc. Its solidification by the cold is due to the fact that cold is a form of condensation. The chief interest of Diogenes is a physiological one, of the same character as that of the pseudo-Hippocratean literature, and there is much to be said for the view that the writers of these curious tracts made use of him very much as they did of Anaxagoras and Heraclitus. Living creatures arise from the earth, doubtless under the influence of heat. Their souls are air, and their differences are due to the various degrees in which it is rarefied or condensed. No special seat, such as the heart or the brain, is assigned to the soul; it is simply the warm air circulating with the blood in the veins. The views of Diogenes as to his theory of sensation amounts to this, that all sensation is due to the action of air upon the brain and other organs, while pleasure is aeration of the blood. But the details of the theory can only be studied properly in connection with the Hippocratean writings; for Diogenes does not really represent the old cosmological tradition, but a fresh development of reactionary philosophical views combined with an entirely new enthusiasm for detailed investigation and accumulation of facts, in a way a data-driven complete archaism with respect to the creation of hypothesis-driven Science that other philosophers developed.

~420 BC Democritus (Abdere 460 - 370 BC) further develops the atomic theory. His main stance is that atoms whirl in the void, where they can combine together in all varieties of forms. This reconciles both the Parmenides view of unchanging matter, and the Heraclitus view of ever changing matter.

441 BC Melissos (Samos, 500 - 440), commanding the float at Samos defeats Pericles. He states that the laws of nature are the same everywhere in the Universe.

~400 BC Hippocrates (Cos 460 - 377) founds the profession of medicine in Greece, with scholars studying under the protection of Asklepios, the god of Health.Among many observations, mostly inaccurate, Hippocrates determines that the male contribution to a child's heredity is carried in the semen. He founds the Asclepiades, a school of medicine that was to subside for several centuries. One of the things for which he is remembered is his theory that the human body is composed of the four elements (earth, air, fire, water) plus four fluids or humors: αιμα or blood, produced by the heart; χολη or yellow bile, produced by the liver; μελανχολη or black bile, produced by the spleen; and φλεγμα or phlegm, produced by the brain. Hippocrates is said to have established the oath that all men professing medicine must obey:

I swear by Phoebos the Physician and Asklepios and Health and all Heal, and all the gods and goddesses, that, according to my ability and judgement, I will keep this oath and this stipulation. I reckon him who taught me this art equally dear to me as my parents, to share my substance with him, and relieve his necessities if required, to look upon his offspring in the same footing as my own brothers, and to teach them this art, if they shall wish to learn it, without fee or stipulation and that by precept, lecture and every other mode of instruction, I will import a knowledge of the art to my own sons, and those of my teachers and to disciples bound by a stipulation and oath according to the law of medicine, but to none others. I will follow that system of regimen which, according to my ability and judgement, I consider for the benefit of my patients and abstain from whatever is deleterious and mischievous. I will give no deadly medicine to anyone if asked, nor suggest any such counsel, and in like-manner I will not give to a woman a pessary to produce abortion. With purity and with holiness I will pass my life and practice my art. I will not cut persons laboring under the stone, but will leave this to be done by men who are practitioners of the work. Into whatever houses I enter, I will go into them for the benefit of the sick, and will abstain from every voluntary act of mischief and corruption and further, from the seduction of females or males, of freemen or slaves. Whatever, in connection with my professional practice, or not in connection with it, I see or hear, in the life of men, which ought not to be spoken of abroad, I will not divulge as reckoning that all such should be kept secret. While I continue to keep this oath, unviolated, may it be granted to me to enjoy life and the practice of the art, respected by men, in all times, but should I trepass and violate this oath, may the reverse be my lot.

The Greeks use a water clock, which measures the outflow of water from a vessel, to measure time.

~390 BC Platonos (Plato) (427 - 347) summarizes the theories developed, but never written, by Socrates. He states that the world as we understand it is a projection of Reality, to which we have thus indirectly access. This leads him to look for Universals (archetypes) to describe Reality, including biological forms and species. This is often in line with the development of pythagorean science and places the study of mathematics at the root of philosophy. Among the many things for which he is remembered is his idea that there are two worlds. The world that we see is just a reflection, an imperfect image of the real world. It is transitory, and will decay. The real world which we cannot see directly, is good, perfect, eternal, and static or unchanging. In this way Plato conciliates Parmenides and Heraclitus, in a way that differs from the way the Atomists chose. In the real world, there is obviously no variation or change, nor need for any, because all the organisms there, the Archetypes, are perfect. The variation we see among organisms here is because they are imperfect copies of the real Archetypes in the real world.

~350 BC Aristotle (Stagiros, 384 - Chalcis, 322), one of Plato’s most famous pupils, creates the first major rules of logics, which we know today as first order logics. This is at the root of all hypothetico-deductive methodology. Logics derives from geometry. The principle of the excluded party (this or that, and not both together) means simply that one cannot have two solids at the same time at the same place. Aristotle defines ten categories needed to represent knowledge: ουσια, ποσοτης, ποιοτης, προς τι, κεισθαι, εξις, τοπος, χρονος, πραττειν, παθειν (in latin essentia, quantitas, qualitas, ad aliquid, situs, habitus, locus, tempus, agere, pati). The corresponding classes are kept till their redefinition by Immanuel Kant during the eighteenth century. Aristotle groups 500 known species of animals into eight classes. In terms of the organization of the universe, Aristotle asserts that the Earth is both the center of the universe and, following Empedocles, one of the four primordial elements. Earth is round. It is the first sphere followed by spheres of water, air, and fire in that order, in their proper places (this follows Anaximandre, with spheres instead of cylinders). This order follows the reasoning of Anaximenes based on the fact that a thrown clod of earth always falls, as does rain, while flames of fire constantly ascend to their sphere. The harmonious relationships and interworkings of these spheres is inspired from Plato, it can be perceived as a celestial music: the music of the spheres. Above fire is the Moon, and this sphere delimits matter of a different kind. Beyond the Moon are spheres for the Sun, the planets, and the stars, which are carried around the Earth in daily, complicated inclined orbits. All matter inside of the Moon’s orbit is different in kind from matter above the Moon. Reminiscent of Plato’s ideas, Aristotle theory states that terrestrial matter decays and is ephemeral, while celestial matter, the aether, is unchanging and eternal. This idea was subsequently borrowed and incorporated into much Christian beliefs as the location for Heaven, and thus was important later in the rejection of Copernicus and Kepler as heretics because they said the Earth was “just another planet” revolving around the Sun. The implication of a Sun-centered system was definitely not a reassuring thought to Medieval Christians who thought of heaven as the place in the aether where would go all the Plague victims who were Christians when they died. As evidence for his view of a round Earth, Aristotle cites examples of things like how ships disappear over the horizon, mast last, as though sailing around a curve. Heraclides of Pontus (388 - 315), another pupil of Plato is one of the first people to say that the apparent daily rotation of the heavenly bodies is not due to their motion, but rather, due to the rotation of the Earth around its own axis. He also states that Venus and Mercury revolve around the Sun, not the Earth. These ideas were not well-accepted by people who thought of down as “down,” not “to the center,” yet these two discoveries constituted important steps toward the Copernican theory.

Rain is measured in India on a regular basis. Iron used as a basic working material in China. Chinese astronomers describe 115 stars and 28 constellations with their coordinates.

332 BC Alexander the Great is crowned Pharaoh of Egypt in Memphis. It may be that the enthronement as Pharaoh included divine honours to Alexander. It is a fact that Persian rule in Egypt, in a strange contradiction to the Persian treatment of most other conquered nations, had been oppressive and had included the desacration of Egyptian holy shrines. The popular image of Alexander being welcomed as the liberator of Egypt, although Arrian limits this 'friendliness' to the Persian governor Mazaces, might be rather realistic. The whole country of Egypt falls into Alexander's hands without a single blow.

331 BC Alexander is back from a 1100 km detour in Lybia, where he consulted the oracle in Siwa. He is said to establish Alexandria on the Egyptian coast, the future metropolis of the Hellenistic world (although both Arrian and Plutarch record the foundation of Alexandria before the Siwa episode.) All our sources state that, after becoming master of Egypt, Alexander felt a strong urge (or 'pothos' if you like) to visit the oracle at Siwa. The Siwa oasis was then called Ammonium or Hammon, its inhabitants Hammonii. It was considered to be one of the three great oracles in the ancient world, together with Delphi and Dodona in Greece. The priests of these oracles stayed in contact with each other. Especially during the oppressive Persian reign, for the Siwah priests this contact might have been quite valuable. Within the polytheistic view, there were little problems identifying the Egyptian Ammon, the Greek Zeus or the Roman Jupiter as one and the same deity. Halas ammoniakôn (ἁλας άμμονιακων ammonium chloride), which much later played such an important role in bridging mineral chemistry with organic chemistry, is discovered at the temple of Zeus Ammon in Lybia.

~330 BC Theophrastos (Eresos, 372-287) describes more than 550 plants in a treaty that was to be copied for many generations until printing was invented in Europe. The Greek explorer Pytheas of Phoceus (Marseilles) reaches Britain.

~325 BC Alexander the Great orders his admiral, Nearchus, to explore the Indian Ocean, Persian Gulf, and Euphrates. Alexander’s conquests bring much of the known world under Graecian domination, including introduction of Greek language, thoughts, and philosophies in areas where these were previously not known.

~320 BC Aristotle states that the male provides the form and the female the raw material for the construction of their offspring. His refinement of the systems of animal and plant classification has profoundly influenced the course of biological thought ever since. His classification system includes what was later called in Latin the Scala naturae. He states that all organisms are arranged in a hierarchy from simplest to most complex, like rungs on a ladder with no vacancies, no mobility, and no change possible since all the spots are full. This idea also was to be borrowed by early Christianity where it replaced the archaic Hebrew concept of “Let the Earth bring forth. . .” Our current technical terms “genus” and “species” are Latin translations of the Greek words first used by Aristotle. Aristotle thought that pangenes, particles representative of the various organs, pass from those organs to the reproductive elements (whatever they may be) and convey their own nature/characteristics to the a preformed, tiny human that just grows in the mother. This belief was held by people up through and including Darwin (in particular by Charles Bonnet), and has led to some very interesting folkloric explanations for birthmarks and birth defects justly ridiculed by Maupertuis. Aristotle speculates whether an embryo just grew/enlarged from the preformed child or undergoes development from some undifferentiated (no distinct body parts) unit to a differentiated embryo. This speculation led to 2000 years of debate and controversy. Praxagoras of Cos discovers the difference between the arteries and the veins.

~300 BC Diocles of Karystos (? - 293) writes a book that advances the knowledge of anatomy. He tries to fathom the causal connection between symptom and disease, in which endeavours he is imitated by Praxagoras of Cos, who establishes the diagnostic importance of the pulse. Epicurus (341-270) expands the theory of the Atomists. Some of his work is summarized in Diogenes Laertius Book X. In fact Epicurus does not improve on the works of Leucippus and Democritus, but, rather, regresses. Rather than propose that the movements of atoms is symmetrical in its principle (i.e. has no preferred direction) he proposes that there is a preferred direction from "up" to "down", like in rainfall. This forces him to add a principle of some kind of shock (πνηγη) to make them collide and interact.

~290 BC Euclid of Alexandria (325 - 265) writes his "Optica" which is the first Greek work on perspective. Euclid also writes the following books which have survived: "Data" (with 94 propositions), which looks at what properties of figures can be deduced when other properties are given; "On Divisions" which looks at constructions to divide a figure into two parts with areas of given ratio; "Phaenomena" which is an elementary introduction to mathematical astronomy and gives results on the times stars in certain positions will rise and set. Euclid's following books have all been lost: "Surface Loci" (two books), "Porisms" (a three book work with, according to Pappus, 171 theorems and 38 lemmas), "Conics" (four books), "Book of Fallacies" and "Elements of Music".

~265 BC First contact of the Romans with Greek medicine through prisoners of war.

263 BC Travelers from Sicily bring the sundial to Rome, where it is displayed on the Forum.

~260 BC Archimedes of Syracuse (287-212) applies the method of exhaustion, which is the early form of integration, to obtain a whole rangeof important mathematical results. He also gives an accurate approximation to p, showing that the exact value lies between the values 310/71 and 31/7. This he obtains by circumscribing and inscribing a circle with regular polygons having 96 sides. He shows that he can approximate square roots accurately. He invented a system for expressing large numbers. In mechanics Archimedes discovers fundamental theorems concerning the centre of gravity of plane figures and solids. "On floating bodies" is a work in which Archimedes lays down the basic principles of hydrostatics. His most famous theorem which gives the weight of a body immersed in a liquid, called Archimedes' principle, is contained in this work. He also studies the stability of various floating bodies of different shapes and different specific gravities.

~240 BC Eratosthenes of Cyrene (of Greek or Chaldean descent) (~276-194) suggests that the Earth moves around the sun and maps out the course of the Nile. He notes that during the spring or autumn equinox, the noon Sun is directly overhead for residents of the (south) upper Nile area, but not at Alexandria, in Northern Egypt. There, the Sun was 7° off from straight up. Since this is about 1/50 of 360°, he calculates that the distance from Alexandria to the upper Nile, which was known, is also 1/50 of the circumference of the Earth. His calculations came very close to modern calculations: the diameter which he calculated in this way is only100 km off from the currently accepted value of the diameter of the Earth. Thus, not only is Earth round, but we can measure its circumference. This was not accepted for many centuries. For several decades, Eratosthenes serves as the director of the famous library in Alexandria.

~220 BC Apollonius of Perga (Perga, 265 - Alexandria, 170) postulates that the planets revolve around the Sun and the Sun revolves around the Earth. Apollonius is believed to be the inventor of the system of epicycles and eccentric circles, used extensively by Hipparchos of Nicaea. He also wrote a monumental treatise on conic sections "On Conics". In this treatise, the term ellipse is first used.

206 BC - 220 AD During the Han period, mathematics, coming from an unknown origin possibly from India, develops briefly in China. This science is soon almost forgotten, to be replaced by the study of proper behaviour of the citizen in the Empire rather than the cultivation and construction of knowledge (development of Confucean ethics instead of Science and Philosophy).

~200 BC Marcus Porcius Cato (234-149) publishes a treaty on agricultural techniques De agricultura. The use of gears leads to invention of ox-driven water wheel for irrigation.

~ 160 BC The first Westerner to document the therapeutic use of leeches is Νίκανδρος ὁ Κολοφώνιος Nicander of Colophon (Clarus, near Colophon 200-130) in his medical poem, Αλεξιφάρμακα Alexifarmaka. Nicander describes poisons in general, analyses 19 specific poisons (8 animal and 11 from plants), and lists appropriate cures. He subsequently writes many books, in particular about medicine and animals.

159 BC The first water clock (clepsydra) is displayed in Rome.

~140 BC Hipparchos of Nicaea (190 -125) , makes important astronomical discoveries and invents trigonometry. He creates the first catalog of the stars, showing their brightness and position. He also discovers the precession of the equinoxes by comparing star observations of different years and noticing that the stars had shifted eastward. He explains these facts by a slow forward motion of the equinoxes. Crates of Mallus forms his great globe of the world.

124 BC The recruitment of administrative personnel in China is performed by a nation-wide competition. The applicants are supposed to have an exhaustive knowledge of the classical texts (meaning texts dealing with behaviour and social rules, including formalisation of Art, but no Science whatsoever). This interesting "democratic" system lasted for two millenia and fixed China to a rigid pattern of behaviour for all this period of time, preventing access to Science because of the content of the examinations.

~100 BC The Romans speculate that mares can be fertilized by the wind.

~70 BC Lucretius (99 BC - 55 BC) in his De Rerum Natura develops the atomic theory and uses it to explain Reality. He propagates the error of Epicurus under the term clinamen.

63 BC Pompeius’s battles and conquests lead to Roman rule of most of the western world.

January 1, 45 BC On the advice of an Alexandrian astronomer, Julius Caesar decides to correct the problem of the non integer number of days in the year by adding a day to the calendar every fourth year. It had always been difficult for humans to devise a calendar that works precisely because the solar year is not exactly 365 days long and the lunar month is not exactly 29 days. This makes up for the 365.25 days of the regular year.

~0 AD-1452 begins the Christian era, with the spreading of a sect derived from a proselytic Israelit sect (Essenians) based on the sayings of prophet Isaiah, among free men but also among slaves. This religion had to have a decisive impact in the development of Science by its role in transmitting and interpreting Greek knowledge into its own categories. Perhaps the most important contribution of this religion to science is its emphasis about the universality of knowledge, and the need to spread it throughout the world (still active today).