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4.5 - Dating Stone Tools and 4.6 Anatomical Evidence for Evolution -…
4.5 - Dating Stone Tools and 4.6 Anatomical Evidence for Evolution
Intro
We can use stone tools found as part of archaeological digs as evidence for human
evolution
It is clear how stone tools have become more complex as our brains evolved in
complexity
Stone Age Tools
Early Stone Age tools - Homo habilis (1.5 million years ago)
Used basic pebble tools (‘Oldowan tools’) created by smashing rocks together
These tools had simple uses, such as cracking nuts
Late Stone Age tools - Homo neanderthalensis (40,000 years ago) and modern Homo sapiens
These more advanced species used pointed arrowheads, spears and hooks
This enabled more advanced tasks to be carried out, such as catching fish
Anatomical Features
Looking at how anatomical features developed over time using fossils also provides important evidence for evolution
Pentadactyl Limb
This can be seen in a number of organisms, implying that they all come from a common ancestor - and that each ‘branched off’ at some stage of evolution
This could have been due to different selection pressures within different environments
A pentadactyl limb is a limb with five digits
Human Hand
The human hand has five digits (four fingers and a thumb), but bats, cats, horses and birds also have this pattern within their limbs
However, that does not mean that we evolved directly from these animals but humans are distantly related to them via a common ancestor
Dating Tools
We can date these tools using two main methods
Radiometric Carbon Dating
By looking at the natural radioactive decay of an isotope of Carbon (Carbon-14) we can estimate how long ago an organism lived
If any once-living material is found with a tool, such as a piece of wood or fur, we can date this to find the age of the rock
Stratifying Rock Layers
Looking at the layer of sediment in which a rock was found is a useful tool for archaeologists
Each layer of sediment, and everything within it, must have been formed at the same time
Therefore, we can date once-living fossils in this layer and use this to estimate when the tools were formed