The claim that Homo erectus had "lower mental ability than modern humans because their brains were smaller" is contradicted by modern research on the possibility to delay the symptoms of dementia by brain exercise. It is possibly to keep dementia completely free from cognitive symptoms until a critical limit slightly below half average Homo sapiens neuron count, where cognition inevitably crashes. The existence of a critical limit makes sense in the context of probabilistic (as opposed to digital) neurology. With probabilistic neurology, the point in having much brain capacity is not processing many information bits, but rather precision, since the neurons act as "vote counters" in the brain network. But the more neurons, the less imprecision there is left to correct, until neurological precision gets functionally indistinguishable from infinity, at which point further increase of neuron count is pure back-up redundancy.
Apelike growth rate in early erectus forms may however have decreased their learning ability. But as shown in "Human Ape", the difference in general intelligence between humans and apes are not reducable to mental age. For instance, apes do not investigate the causes of faliure in tasks. That lack can be naturalistically explained by limited neuroprecision and thus conceptual discrimination making such investigation pointless to impossible. Kanzi the bonobo, for instance, cannot conceptually discriminate between the word/lexigram "chase" and the word/lexigram "get". There is however archaeological evidence that Homo erectus could and did investigate the causes of faliure.
On the genetics of Homo erectus, it would be appropriate to mention the variability theory from Theodosius Dobzhansky´s "modified polygenism", that all sapiens alleles existed at a low but non-zero frequency within the individual genetic variation in all erectus populations, and that sapiens emerged through diversity reducing selection without any need for new mutations. Dobzhansky based this view on the fact that it takes many generations for mutations from their first occurrence to their selective standardization in the population. That model has been ridiculed by neutralists, but are vindicated by the discovery that so-called "junk DNA" regulates gene activity, and that half the total DNA difference between (modern) humans and chimpanzees are in the parts of regulating non-coding DNA that regulates gene activity in the brain. That extremely uneven distribution of differences, some loci differ far more between humans and chimpanzees than other loci does, is impossible to explain by neutralistic population effects, proving that human evolution was predominantly selectionist. 188.8.131.52 (talk) 04:45, 16 October 2011 (UTC)Martin J Sallberg
- I believe no such Dobzhansky's "modified polygenism" ever existed. In fact it sounds more like Carleton Coon's theory Dobzhansky disputed: "When Dobzhansky was asked to review The Origin of Races for the literary journal Saturday Review in September 1962, though, his reaction was more qualified. He praised the descriptions of hominid fossils which Coon provided, but objected to the idea that subspecies of Homo erectus had evolved into sapiens independently. For Dobzhansky and Coon, the debate about race concepts was also about evolutionary mechanisms. In The Origin of Races, Coon suggested a mechanism for the parallel evolution of isolated subspecies through the simultaneous elimination of unfit genes from multiple populations. In his review, Dobzhansky rejected this mechanism, writing that such parallel evolution would require a “mystical inner drive that propels evolution.”" 
There are six Talk Origins pages in the external links, which seems a little excessive. If there are good reasons for citing them, then I suggest they be incorporated into the article as citations; otherwise delete them or trim down to one or two most relevant as external links. WẽãšẽĩõĩďMethinks it is a Weasel 18:45, 17 December 2011 (UTC)
- (Big gay penis joke incoming) — Dysk (contribs) 15:37, 23 May 2019 (UTC)
- How soon after realising that 'bits of charcoal out of the fire left marks' did people start drawing 'naughty pictures'? 184.108.40.206 (talk) 16:08, 23 May 2019 (UTC)
Image is wrong
The image used in the article is wrong. The Turkana Boy is a Homo Ergaster fossil; in fact, it’s actually the most famous fossil of that human species.