ANTC16 – Lecture 4
Carl Linnaeus (swedish) – He was a botanist and a natural theologian who created a taxonomic classification
system and classified animals in his book systema naturae. Linnean hierarchy consists of kingdom, phylum,
class, order, family, genus, and species.
Linnean hierarchy of humans
Kingdon – Animalia
Phylum – Chordata
Class – Mammalia
Order – Primates
Family – Hominidae
Genus – Homo
Species – Homo sapiens
Binomial (containing 2 names)
Species contain genus and trivial name
Species name contains some info about how that animal is supposed to be related to other things.
Can easily change if ideas of relationships change.
Movement for uninominal species names.
The genus and species must by italicized
LCZN provides the rules for classifying animals it states that once someone names a species it cannot be
The formal name for human is: Homo sapiens Carl Linneus 1758
The LCZN also controls the format of the group (example: all family names must end in – idea)
There are two problems with taxonomy
1. How to identify species
2. How to recognize and designate groups of species (higher level taxonomy)
How to identify species
There are 20 competing definitions for species. The biological species concept (BSC) was written by Ernst
Mayr and it states ‘species are groups of actually or potentially interbreeding natural populations,
reproductively isolated from other such groups’
The reason this makes sense is b/c if you have 2 groups that continue to interbreed, they’re not going to become
When we do any type of analysis where we treat species as distinctive things, we’re assuming they can’t
interbreed b/c otherwise, any similarities between them could just be a product of interbreeding and not
common ancestry. Fundamentally whether or not we are components of BSC, most biologist behave as
though this is true.
This is difficult to apply this species concept to fossils because
- We can’t tell reproductive patterns
- The concept doesn’t account for temporal differences
One of the ways that we can tell the reproductive patterns of a fossil is by considering some morphological
criterion but even modern species differ in how much variability they include (example: some species are
sexually dimorphic while others aren’t) ANTC16 – Lecture 4
Ideally you would like to find fossil species that would be comparable to modern species b/c otherwise when
you do an analysis with e.g.Ppan paniscus and Homo habilis, you want those to be as equivalent as possible
in terms of what they mean. So what we would like to do is use the variation we see in good modern
biological species to constrain how much variation should be in the fossil species.
Varying levels of sexual dimorphism
Sexual dimorphism is related to the intensity of malemale competition within a species
- Gibbons are similar in body size (6kg) and both sexes have large canines
- Gorillas are very sexually dimorphic (males can be twice as large as females) they are also dimorphic in
- Chimpanzees are slightly sexually dimorphic: they have slight differences in size and they show canine
- Mandrills have high levels of sexual dimorphism (colour, size and canine)
- Lemurs have low levels of sexual dimorphism
Humans also show some levels of sexual dimorphism: an average male weight is about 86.6 kg while average
female weight is about 74.4 kg. We are more dimorphic than chimpanzees but humans don’t show canine
some species of fossil primates were more sexually dimorphic than any living species
Lufengpithecus is an extinct ape, which is placed in the same subfamily as orangutans (Ponginae). This species
is sexually dimorphic. In this species male have a sagittal crest while females don’t. Males also weigh two
and a half times more than females (male orangutans are 2.2 times larger than females).
Using modern primates as the basis for recognizing species in the fossil record can be possible but it can be
problematic if there are no good modern species that exists for comparison.
Why should we assume that modern primates provide the limits for what is realistic for a species? Most
primates are extinct 99% of the life that has been on earth is extinct, and we know that primates get larger
than any living primates in terms of body size s/a Gigantopithecus which was bigger than any living primates
so why shouldn’t there be more variability in the past? ANTC16 – Lecture 4
Ackerman et al., 2006: fig. 3
Looking at the record of Early Homo, they both come from the same time and place (H. rudolfensis and H.
habilis craniums). If you apply a gorilla model, you could argue the amount of size variation in a single
species but that implies that 1) our ancestors were much more dimorphic than us and had fundamentally
different social structures 2) the pattern of variation in other things in size were different in the past b/c this
supposed female has much larger brow ridges than the supposed male. It’s not just a semantic issue b/c it
does influence how we think about our evolutionary past if they are two separate species that means that
they would have been competing and only one of which could be our ancestor whereas if it was one species
then that means it would have been very different from us in terms of its presumed pattern of social behvr
so it does actually matter in terms of understanding our past.
Homo rudolfensis and Homo habilis are found around the same place (geographically) and at around the same
time (temporally) – baboons can be used as models
There are two species of baboons, which live in Africa: Olive baboon and the Yellow baboon. Both of these
species look different from one another but they have been known to interbreed and produce hybrid
offspring, which are larger, reproductively capable and have a greater number of teeth
Our ancestors (Homo sapiens neanderthalnesis) were very different from humans today. An odd trait is that
females exhibited larger brow ridges than males (this is problematic and hasn’t been solved yet)
Homo sapiens were capable and have bred with Homo neaderthalnesis but the hybrids are hard to distinguish.
They may look like either or. ANTC16