Human Canopy Evolution

For more than 50 million years, the canopy environment has placed stringent evolutionary conditions upon existence within its domain. Primates are a result of that process. Some examples of primate adaptations traditionally attributed to evolution within the canopy include binocular and color vision, long arms and legs, fingernails, grasping thumb, broad shoulders, enlarged brain, vertical posture, giving birth to one young, and a head that sits at a right angle to the spine. Certain features once thought to have originated in the terrestrial environment have now been added to this, including bipedalism among large-bodied apes and a long, opposable thumb. Over the last decade and a half, fossil discoveries have continued to strengthen the view of the canopy as a source of protohuman adaptations.

Since the time of Darwin, theories of human evolution have taught that the arrival of bipedalism brought an end to our dependence on trees. That event cut us loose from our boorish primate origins, freeing us to fulfill our destiny. Arrival at the ground was a fundamental turning point in our lineage that set our hands free to work miracles, and with that, we never once looked back at our arboreal birthplace. Yet since the discovery of Australopithecus afarensis,there has been a growing list of potential ancestors that have turned this view upside down. Not only were they active bipeds, they were also active climbers. These climbers are prominent names in our ancestry, such as A. africanus, Homo habilis, and H. rudolfensis, to name a few. Naturally, the ancestors of those early bipeds were also thought to have been climbers. As shown below, even H. erectus, who is viewed as exclusively terrestrial, used tools designed for canopy applications.

Oddly, the knowledge that our early bipedal ancestors spent considerable time in the canopy has not percolated down into theories about the evolution of human nature and the brain. The original theories, formulated from strained academic efforts to hide our affinities with apes over the past 150 years, promote an outdated terrestrial view of evolution that remains largely accepted and intact. “Canopy theory” unifies myriad disparate data into a single, cohesive, commonsense framework. Comparing terrestrial mammalian evolution during the Cenozoic with primate and marine mammal evolution raises doubts that the terrestrial environment could have been a habitat that promoted encephalization. Canopy theory encompasses early primate evolution and shows that the arboreal process of primate encephalization did not cease once our ancestors arrived at the ground. On the contrary, it shows that a reinvigorated arboreal encephalization process ultimately led to the human-sized brain. To demonstrate the strength of the canopy viewpoint within the space permitted, several of the more intractable problems that, as yet, lack satisfactory explanation will be discussed. These include the loss of thick body hair, tree platforms, and early weapons, such as the Acheulean hand axe.