After the speculation about the origins of Cheddar man, a nice topical look at what is currently known (or thought to be the case) about primate and human evolution has been made available (https://www.theguardian.com/news/2018/feb/12/tracing-the-tangled-tracks-of-humankinds-evolutionary-journey). One of the more striking observations is that the average size of the modern human's brain has reduced by some 5-10% over the last 200,000 years. The brain is a greedy organ, consuming around 20% of our energy and 'domestication' (our domesticated animals have smaller brains than their wild progenitors) may mean that current humans can get by with smaller brains than our ancestors (who had more to worry about or to deal with?). Pretty obviously, babies with smaller heads are also less likely to lead to problems at parturition (so this factor could have direct selection value).
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