Early Hominid Habitats

Speciation events (like the emergence of the first hominids) tend to coincide with major climatic changes that dramatically alter or fragment the established habitat.

Such changes tend to effect a wide range of animal lineages at the same time.

Consequently, the fossil record of these animals can act as an indicator of habitat change.
Palaeoecology is the branch of Palaeontology concerned with reconstructing ancient climates, landscapes and ecosystems.

One way of doing this is to make use of the known relationships between living faunas and their habitats. For example, if ungulate faunas living today are known to inhabit wooded grasslands, it is likely that ancient antelopes of the same kind also lived in wooded grasslands.

So the fossil remains of extinct faunas can provide clues to the nature of the extinct environments in which they lived.

• How can palaeoecology help us identify the habitats in which hominids evolved?
• And when we know something about the habitats, are there ways of inferring (or "modelling") the behaviour in those habitats?

Faunal Correlation

If hominid fossils are found in thecompany of fossils belonging to savannah mammals, it is probable that the hominids also lived on the savannah.

Quite a lot of evidence now supports the view that the emergence of the hominids had much to do with the colonisation of wooded savannah by a forest-living ape.

The adaptations of the ape to arboreal life would have predapted it to striding about the savannah landscape.

During the Miocene, the great expanses of forests that covered the tropical and sub-tropical regions of Africa began to break up due to climatic change.

One consequence of these changes was the emergence of the African savannah and its characteristic fauna of ungulates, primates and carnivores.

Among the primates that colonised this new habitat were the first hominids.

In the process of colonising it they became bipedal, big-brained, linguistic and cultural.

• What were the selective pressures that favoured these developments?
• Scavenging? Co-operative hunting? Migration?

Modelling

Comparison is a core intellectual tool of the biologist.

With care, it can be used to analyse both the functional anatomy and the behaviour of extinct species.

A common technique is to use relationships established among living animals to make predictions about extinct relatives.

This approach can be illuminating, but it is also fraught with difficulties, not least because it assumes that the living and extinct forms were built in accordance with exactly the same design principles.

Comparative methods can also be used to analyse the behaviour of extinct forms, e.g.:

• comparing the femurs of living primates having different modes of locomotion allows fossil femurs to be interpreted in locomotor terms;
• mammals characterised by polygyny tend to exhibit sexual dimorphism, so it might be reasonable to infer that sexually dimorphic fossil primates were also polygynous in life;
• micro-toothwear patterns on fossil teeth can be related to similar patterns on extant teeth to reveal information about the diet of extinct forms.