First published in The Reign of Mary, Issue #123
John Locke (Internet Encyclopedia of Philosophy)
I am taking some liberties in calling Turkana Boy a ; he is technically a member of , which is often considered ancestral to , which is the Asian variant’s name. There is great debate regarding how the human family tree branches between and . Some call the various -type species all subspecies of , while others argue for several distinct species. I will not stray far from the orthodox narrative here, for good reason. The reconstructed early human tale is based on very limited evidence, but that evidence will only grow over time, and the tools and techniques for using them will become more sophisticated. Although there may be some upcoming radical changes in the view of the early human journey, efforts of countless scientist and fossil hunter lifetimes support the narrative that this essay sketches, and I respect their findings and opinions, even though I acknowledge many limitations. The human ego, it seems, becomes more involved as the story of life on Earth moves closer to its human chapters.
The mother who says having these two ..
A has challenged The Expensive-Tissue Hypothesis, at least as far as robbing energy from the digestive system to fuel the brain. The study compared brain and intestinal size in mammals and found no strong correlation, but there was an inverse correlation between brain size and body fat. But since human fat does not impede our locomotion much, humans have combined both strategies for reducing the risk of starvation. Whales have bucked the trend, also because being fatter does not impede their locomotion and provides energy-conserving insulation. A human infant’s brain uses about 75% of its energy, and baby fat seems to be brain protection, so that it does not easily run out of fuel. However, the rapid evolutionary growth of an energy-demanding organ like the human brain seems unique or nearly so in the history of life on Earth, and comparative anatomy studies may have limited explanatory utility. There are great debates today on how fast the human brain grew, what coevolutionary constraints may have limited the brain’s development (, , ), and scientific investigations are in their early days.