Before the Darwinian Revolutions
Standard view in Antiquity = species are natural kinds, which means that they are fixed groups (do not turn into another group / do not transform / transmute / evolve)
- you can carve out distinct kinds of species in nature
- this coincides with the structure and organization of the natural world
- this was not just the view in biology, but also in other sciences
Nowadays, in evolutionary biology, it is controversial to say that they are natural kinds and it is harder to carve out distinct kinds
Aristotle argued against evolution (instead they are fixed natural kinds) and against extinction. Lucretius argued for extinction but not evolution.
Empedocles (5th century)
Empedocles element theory =
- claimed there were 4 roots (earth, air, water, fire) and 2 forces / motive principles (Love, Strife)
- Love = operates to unite unlike things
- Strife = operates to separate unlike things
- when Love is ruling the cosmos, the four roots are mixed together
- when Strife is ruling the cosmos, the four roots are separated into distinct layers
- and there is an in-between
Empedocles, as quoted in Simplicius’ Commentary on Aristotle’s Physics 371:
“…during the rule of Love there came to be by chance first of all the parts of animals, such as heads and hands and feet, and then these ‘man-headed oxen’ came together, and conversely there sprang up ox-headed men… And as many of these as were fitted together to one another so as to ensure their preservation, became animals and survived… For all that did not come together according to the proper formula perished.
For Empedocles, animals could have characteristics because of accidents. For Empedocles, in nature, there could be accidents and could form monstrous creations.
Aristotle’s Parts of Animals 640a on Empedocles: “…animals have many characteristics that are the result of incidental occurrences in their formation—for instance the backbone is as it is [divided into vertebrae] because the fetus becomes contorted and so the backbone is broken.”
Aristotelian Biology
A key figure that Aristotle was responding to was Empedocles, arguing instead that everything in nature has purpose, and that the cosmos is fixed.
Aristotelian biology was based on the standard view that there are fixed natural kinds.
Aristotle’s four causes = we should account to four causes when explaining something:
- Hylê (matter) = material cause
- morphê (shape) = formal cause
- moving/efficient cause = what initiates/arrest a change
- that for the sake of which (Final/efficient) = the purpose or the why
For rainfall,
- material cause = water
- formal cause = rain droplet
- Efficient cause = condensation
- Final cause = to water the crops (for the sake of the crops)
For a person,
- material cause = flesh, blood, etc.
- formal cause = human
- efficient cause = the parents
- final cause = to be an adult who lives well
for living things, the formal cause is the species
For Aristotle, there does not need to be a creator god for their to be purpose. Nature gives purpose.
In antiquity, there was a common view of spontaneous generation = things forming out of nowhere in the right conditions. E.g. the correct conditions and the correct materials could create a mollusks
Aristotle’s Physics 2.8.199a:
“If then, it is agreed that things are either the result of coincidence or for the sake of something, and these cannot be the result of coincidence or spontaneity, it follows that they must be for the sake of something; and that such things are all due to nature…Therefore action for an end is present in things which come to be and are by nature.”
Aristotle’s Generation of Animals 715b: “Nature always seeks an end.”
Lucretius (90 - c. 50 BCE)
Lucretius was a Roman philosopher who followed Epicureanism.
Poem On the Nature of Things =
- Book 1 and 2: atomic theory
- Book 3 and 4: on the soul
- Book 5 and 6: nature of the world
Epicureanism holds that the Gods did not create the world or humans, and that the gods are like humans, just especially blessed. Instead, Epicureanism holds that the cosmos was created by the accidental movement of atoms.
“For so many first beginnings of things in so many ways, propelled by blows from infinite time until the present day and impelled by their own weight, have been accustomed to being borne along, and to meet in all sorts of ways and to try all combinations, whatever they are able to create when brought together among themselves, that it is no wonder if they also fell into such arrangements
and settled into such movements, as these now by which
the sum of things continues on by renewing itself.” (book 5, line 187 - 190,)
Lucretius holds that the cosmos is formed accidently, but still hold order and regularities (laws of motion). Living things were created from the Earth by spontaneous generation.
Then, you see, earth first produced animals.
For much heat and moisture were abundantly present in the fields.
Therefore wherever a suitable area of space was provided, wombs would grow, clinging tightly to the earth by roots
And then too the earth attempted to create many
aberrations which came into being with amazing appearance and limbs:
the man-woman, in between both but neither, different from each,
some deprived of feet, others in turn without hands,
others also speechless without a mouth, or found blind without sight,
some restricted by the adhesion of their limbs to their entire bodies,
so that they could not do anything nor move anywhere
nor run from evil nor obtain anything they needed.
She created other rnorrsters and aberrations of this sort,
all to no avail, since rlature forbade their growth and they could not attain thc clcsirccl flowering of their age,
nor find food nor join togethcr in that activities of Venus.
For we see that many things must come together for creatures to have the possibility of pounding out generations by propagating:
But since she must have some end to her begetting,
she stopped, just like a woman exhausted by old age. (826)
Species that do not have usefulness to human beings, or lack craftiness, or courage, then they can go to extinct.
Binomial system of classification
Binomial system of classification =
- every species is known by two names, the genesis and the species
- homo = genesis, sapiens = species
- The binomial system was formed to make the naming more concise and more applicable
- created by Swedish scientist Carl von Linnea (Carlous Linnaeus) in the 18th century (1749)
Before the Binomial system, it was a polynomial system. It consisted one word for the genesis, and then a description for the differentia (what makes it different from another species).
morphology = the comparative study of the structure of living things
- this was used to how to distinguish one species from another based on their structure (erect, two-legged, etc.)
Linnaeus system is based on Aristotelian biology
- Like Aristotle, Linnaeus grouped species based on their structure