On the Hunt
Hominins most likely started hunting with weapons more than 500,000 years ago. ~ German archeologist Sabine Gaudzinski-Windheuser
Homo embodied numerous anatomical and physiological changes which became increasingly apparent 2–1.6 MYA. These occurred at different times and sometimes distinctly in different clades.
Bipedalism let these hominins excel at long distance running. No other primate is comparable. In contrast, quadrupeds are faster sprinters, but are not built for distance.
Enlarged hindlimb joints and shorter toes were among the adaptations that afforded hominin long distance endurance. More generally, a gracile body plan helped.
Another facet involved ways to avoid overheating. Loss of fur and the addition of sweat glands were instrumental in keeping cool.
The ability to track down animals over distance had to be complimented by the physical means to bring down prey. The Homo upper body developed for hunting, and warfare, particularly shoulder changes that allowed throwing objects, which other apes are comparatively dismal at. Longer waists were instrumental in distance running and were also important in being able to hurl an object with force via augmented torque production.
A longer waist and straighter upper arm bone appeared with australopiths. The shift in shoulder-socket orientation debuted in Homo erectus. The trade-off in these changes was a lessening ability to climb trees. Arboreal safe haven was forsaken for being able to stand one’s ground.
Evidence indicates that hominins were butchering animals by 2.6 MYA using crudely hewn stone chopping tools. It was not until 500 TYA that spearheads were developed. The earliest heat-treated tools appeared only 72 TYA.
Despite an apparent lack of projectile weapons, indirect evidence suggests that hominins hunted 1.8 MYA. Ambush hunting with rocks and spears at relatively close range would have been lethal for intended targets. Wood spears and other tools were used and might not appear in the fossil record.
Hominin technological innovation for hunting appears meager for nearly 2 million years. Populations continued to be small for that huge tract of time, and only a tiny fraction were likely to be inventive, as remains true to this day. Only with social interchange among groups across considerable distances were the inventions of a few able to disperse. That development was haphazard until populated settlements became the standard of civilization some 8 TYA.
Hunting may have altered sociality. While men stalked game, learning to work in groups, women foraged and cared for offspring.
Sexually segregated groups came together to share food. Such social mores and bonding dynamics prevail to the present.
Male chimps opportunistically hunt in small groups for prey they can overpower. Forest-dwellers grab colobus monkeys, typically younglings. Such hunting is emotionally draining. Adrenaline surges as chimps chase, snatch, and rip monkeys apart with their bare hands.
Chimpanzees in the grasslands of Senegal target galagos (aka bushbabies): small, nocturnal prosimians. They skewer their prey by jabbing sharpened sticks into tree hollows where bushbabies sleep during the day. Galago stickers are more subdued and methodical than the frenzy of colobus killers.
Similar calculation may have characterized early Homo group ambush hunting. This put hominins on the twin paths of easy violence that has characterized the genus ever since: emotively explosive and dispassionate, with the latter being far more terrifying for its unempathic detachment. Hominin societies which relied more on hunting tended to be more warlike – a trend continued into historical times.
Plant foods containing high quantities of starch were essential for the evolution of humans. ~ English evolutionary biologist Karen Hardy et al
Much has been made about increased meat consumption driving greater brain wattage in early Homo by those ignorant about animal intelligence in general and human nutrition in particular. If anything, a diet of carnivorous scavenging would have rendered hominins no smarter than vultures (no insult to vultures intended). Even now, eating meat creates an unfavorable gut microbiome, degrading health and promoting mortality.
Any flesh early Homo consumed would have been raw meat, as cooking had yet to be discovered. The derived nutritional value would have been less than meat seared by heat, and it would have borne a serious risk of pathogens – a risk that survivors would take note of.
The optimal diet to feed the body and brain is from plant sources, high in carbohydrates with appropriate protein.
Hominins may have upped their protein intake a bit by eating grubs and adult insects. The often-bandied conclusion that a meat-heavy diet provoked Homo evolution, particularly cognitive advance, is absurd.
Instead, hominins probably became better foragers, having learned through experience and culture the nutritional and medicinal values of plants and their products. Mashing tubers and other root vegetables, with their ample carbohydrate content, may have been significant. This better explains the evolution of hominin guts and brains.
Protein-laden muscle mass – meat – digests down to animal fat and amino acids: not an apt energy source. Further, the acidic digestive environment and indigestible waste products from eating meat tax the system terribly.
Autophagy – recycling proteins, amino acids, and other nutrients from spent cells – provides considerable readily available structural material needed by the body. Autophagy plays a critical role in body maintenance and longevity. Even slight adaptations in autophagy could account for hominin gut changes.
The hominin brain has long required a lot of energy. That energy has always been supplied by plant foods: high in carbohydrates and providing a surfeit of balanced protein.
Archeological evidence points to hominin descent on a largely vegetarian diet. For one, foraging is much easier, and more reliable, than hunting.
2.3–1.2 MYA, Paranthropus was a robust savanna forager that had a varied seasonal diet, preferring fruit and nuts when available, but resorting to herbaceous vegetation when not – not dissimilar to lowland gorillas. While Paranthropus had a head, jaw, and teeth comparable to a gorilla, it did not have the gorilla gut.
2 MYA, Au. sediba, the last australopith, was a gracile omnivore with a small gut that harvested from the woodlands: living off fruits, nuts, leaves, and sedges, as well as plants such as papyrus or cypress. Small critters, including insects, were likely on the menu. Au. sediba‘s diet, while perhaps higher quality, was not strikingly different from that of chimpanzees.
Homo ergaster (1.9–1.4 MYA) – a putative ancestor to humans – was another omnivore with a small gut. Archeological finds of axes and hides suggests skinning animals, likely for clothing. How much raw meat H. ergaster ate is not known. A safer, more readily available fare was plant tubers. These tough but highly nutritious vegetables were likely processed with stone tools to require less chewing and render them more digestible. As with humans today, juicy tubers and roots were probably an important part of H. ergaster‘s diet, providing ample carbohydrates and protein in a wholesome balance.
Considering the health risks of a diet high in raw meat, and the relative ease of finding vegetative food, it is most likely that a more learned selection of plant produce played a dominant role in the descent of humans, especially before the advent of cooking.
Neanderthals were more inclined to carnivory than other hominins. That dietary preference may have been instrumental in their demise, as its tax on health limited their life at the same time their competitor – Cro-Magnon – was starting to have a significantly longer life span. Longer life meant greater cultural transmission between generations.
The value of steeped experience cannot be overestimated. Elephant groups are led by an elder matriarch. A group bereft of senior leadership fares poorly by comparison.
Seafood shows up on the menu much more recently than other meat. The Chinese were supplementing their diets with freshwater fish 40 TYA, but contemporaneous Mediterranean settlers ignored any watery bounty.