Some technical features of our species worthwhile to consider on this topic:
There are early hominids (this post) and modern hominids.
Modern hominids have a much bigger brain (absolute but more important relative to their size and food intake).
The hominid succes was also boosted by preparing food in a primitive way with fire or fermenting to get a higher yield out of it => causing a smaller belly and freeing resources to sustain a bigger brain (high energy consumption per weight) and enabling better survivability during famine periods.
This bigger brain is for 8% weight composed out off Omega-3 fatty acids.
Savannah food has a low Omega-3 yield, unless you eat enough mammalian brains.
Sea food has it in abundancy.
The hominid development of a bigger modern hominid brain almost must have happened along the seashore.
If the early hominid was succesfull enough to spread all over Africa-Europe-Asia, this Omega-3 brain boosting step may have happened anywhere: both paralel as multiple times.
But it is unlikely that brain boosting phase happened on the big mainlands of the African savannah or Euro-Asian planes.
And for a fact: the lenght of the seashore of the Northern coast of the Mediterranean Sea, Aegian Sea, black Sea is longer than the North and East shore of Africa.
Evidence for the unique function of docosahexaenoic acid during the evolution of the modern hominid brain.
Crawford ,
Bloom M,
Broadhurst CL, Schmidt WF, Cunnane SC,
Galli C,
Gehbremeskel K,
Linseisen F,
Lloyd-Smith J, Parkington J.
Abstract
The African savanna ecosystem of the large mammals and primates was associated with a dramatic decline in relative brain capacity associated with little docosahexaenoic acid (DHA), which is required for brain structures and growth. The biochemistry implies that the expansion of the human brain required a plentiful source of preformed DHA. The richest source of DHA is the marine food chain, while the savanna environment offers very little of it. Consequently Homo sapiens could not have evolved on the savannas. Recent fossil evidence indicates that the lacustrine and marine food chain was being extensively exploited at the time cerebral expansion took place and suggests the alternative that the transition from the archaic to modern humans took place at the land/water interface. Contemporary data on tropical lakeshore dwellers reaffirm the above view with nutritional support for the vascular system, the development of which would have been a prerequisite for cerebral expansion. Both arachidonic acid and DHA would have been freely available from such habitats providing the double stimulus of preformed acyl components for the developing blood vessels and brain. The n-3 docosapentaenoic acid precursor (n-3 DPA) was the major n-3-metabolite in the savanna mammals. Despite this abundance, neither it nor the corresponding n-6 DPA was used for the photoreceptor nor the synapse. A substantial difference between DHA and other fatty acids is required to explain this high specificity. Studies on fluidity and other mechanical features of cell membranes did not reveal a difference of such magnitude between even alpha-linolenic acid and DHA sufficient to explain the exclusive use of DHA. We suggest that the evolution of the large human brain depended on a rich source of DHA from the land/water interface. We review a number of proposals for the possible influence of DHA on physical properties of the brain that are essential for its function. [
7]
, so were the Denesovians and perhaps more....
