Again, there is a whole chapter on vocal chord evolution over a million years.
Papers… not books… scientists write all kinds of speculative stuff on popular science books
Those don’t tend to fossilize well. But with brain size:
Figure 4: Ordinal tool complexity scale (red circles) from Stout (2011) plotted over absolute brain size (in cc) as a function of time from 3.2 million to 10,000 years BP. Scale on right indicates ordinal increases in tool complexity. Abbreviations refer to categories in Stout (2011) Figure 2. UO, unifacial Oldowan; BO, bifacial Oldowan; KA, karari; CLCT, core LCT; FLCT, flake LCT; HC, hierarchical centripetal; CV, cleaver variants; RS, refined shaping; BL, blades; OP, other predetermined; LV, Levallois variants.
Not quite what you’re looking for with language but its interesting to see tool development appears to correlate with brain size for the most part (paper link: Brains, innovations, tools and cultural transmission in birds, non-human primates, and fossil hominins - PubMed).
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Thanks for the article. I will go throught it…
Let me make the observation that considering that Agriculture, pottery, the bronze age etc happenned about 10kya, there should have been a red wall in the graph somewhere thereabouts.
Its a little ridiculous to correlate tool complexity to brain size IMO… after all mig Aircrafts are also “tools”. And if you notice in the graph, there is considerable overlap in brain sizes between humans and Homo Erectus.
Why is this data seen as a correlation between “tool” usage and brain sizes?
If i drew a rectangle at the 1000cc line, we would get a good set consisting of both Homo Erectus and modern humans. Are you suggesting they had similar capacities with respect to tool making?
Isnt this actually evidence that brain size is not the whole story?
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Are they doing that? If you plot it on the same graph it matches the same pattern but there could be other reasons for that. Obviously we know that correlation does not equal causation. Another study was this one that specifically had some links between tool development, brains and language:
One of the interesting things from that study and some others is that language and tool use/making do place similar demands on the brain. So it is not surprising to see such a correlation, not to mention that a separate study looked at the blood flow in ancient hominids and brain size:
From:
http://rsos.royalsocietypublishing.org/content/3/8/160305
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