It’s easy for humans to take food availability for granted in our modern world, but the acquisition of food resources in human history has been a gradual process that required time and energy. Scientists have learned that the strategies humans have employed in acquiring food reveal traits that help explain what it means to be human.
Are Humans Exceptional? One of the major creation/evolution debates of our time concerns the idea of human exceptionalism, which holds that humans differ fundamentally in kind from all other species of life on Earth. Nontheists and theistic evolutionists reject the concept, arguing that the differences between humans and the bipedal primate species that preceded us are not great. They assert that the differences we do possess are the product of natural descent from a common ancestor shared by humans, the earlier bipedal primates, and the great apes. This belief led Charles Darwin to conclude that humans differ only in degree and not fundamentally in kind from nonhuman primates.1
Christians, on the other hand, believe that humans are exceptional and that we differ fundamentally in kind from all other species. This belief is a core biblical doctrine. The Genesis creation accounts declare that humans did not evolve from other primates. Rather, Scripture says that God specially created the first humans, de novo, from the dust of the earth and breathed into them “the breath of life.” The biblical accounts proclaim that humans, alone among all Earth’s life, are created in the “image of God.”
In the debate I had with atheist British chemist Peter Atkins, he challenged me to cite a potential scientific discovery that would compel me to abandon my Christian faith.2 One example I gave was the possibility of scientific discoveries that would prove beyond any shadow of doubt that humans are not exceptional. Conversely, if scientific discoveries show beyond doubt that humans are exceptional, then that find would establish the existence and operation of God. Clearly, a lot rides on whether or not humans are exceptional.
Biological Uniqueness Humans’ spiritual, intellectual, and symbolic capabilities provide the most compelling evidence for exceptionalism. I and my RTB colleagues biochemist Fazale Rana and philosopher Kenneth Samples have written extensively about these capabilities (see the Resources section). However, even at a purely biological level, there is persuasive evidence for human exceptionalism.
For example, relative to chimpanzees, gorillas, orangutans, Neanderthals, Homo erectus, and other nonhuman bipedal primates, humans possess larger brain-to-body mass ratios, unique brain structure, larger blood flow to the brain, longer life spans, higher fertility rates, longer developmental periods, and larger neonates (newborns). The list of biological differences goes on. (You can read about some of them in my previous articles on the uniqueness of human eyes,3 human hearing,4 and human bipedalism.5 You’ll also find additional articles listed under Resources below.)
Uniqueness of Human Subsistence Energetics Recently, a team of eleven scientists led by Thomas Kraft discovered yet another feature of human biological uniqueness.6 In the introduction to the paper Kraft’s team wrote on the discovery, they noted that humans’ many unique biological features place tremendously high energetic demands on human adults. While these demands are easily met by humans living in high-technology, high-wealth societies, they would not have been so easily achieved by the first humans, who had to meet these energy requirements through hunting, gathering, and subsistence farming.
Previous research studies showed that humans possess anatomical advantages over the great apes that make the acquisition of calories and nutrients less costly in terms of energy and time spent. Humans have a combination of anatomical and behavioral traits that reduce the energy needed for walking and searching for food.7 Humans also spend far less time feeding,8 and our digestive organs are smaller relative to total body mass.9 However, the sum total of these anatomical advantages appears insufficient to account for humans’ much greater energy demands.
Kraft and his colleagues used field studies to directly measure the energy costs and benefits of food acquisition, processing, and consumption by gorillas, chimpanzees, and orangutans compared to that of the Hadza hunter-gatherer tribe in Tanzania and the Tsimane forager-horticulturalist tribe in Bolivia. The results of these studies established that humans in hunter-gatherer and forager-horticulturalist societies spend more energy on a daily basis acquiring their food than primates do. However, they also gain far greater rates of return.
Human hunter-gatherers and forager-horticulturalists acquire far more calories and nutrients per hour than comparable species. Consequently, even though these humans spend more energy per day obtaining their food and nutrients, they spend less time doing so. Relative to the great apes, hunter-gatherer and forager-horticulturalist human food acquisition strategies involve high-cost extractive activities and expanded day ranges that deliver far more calories in less time. The studies also showed that food acquisition strategies played a much more significant role than anatomical differences in explaining how humans meet their energy demands.
Philosophical Implications Hunter-gatherer and forager-horticulturalist humans’ high cost but high return strategy for acquiring food is possible because humans are endowed with intellectual and social capabilities that enable increased cooperation, division of labor, and intergenerational food sharing. And though early humans lacked technology and wealth, the time saved in obtaining food and nutrients permitted them to use that time to invent and manufacture more sophisticated tools that produced greater efficiencies in food acquisition. These greater efficiencies, in turn, saved even more time that could be devoted to creating technology and wealth, culminating in advanced civilization. As a practical application for Christians, we possess the wealth and technology today to take the Good News of salvation through the sacrifice of Jesus Christ on the cross to all the world’s people groups, thanks in large part to exceptional characteristics God endowed upon human beings.
Thomas S. Kraft et al., “The Energetics of Uniquely Human Subsistence Strategies,” Science 374, no. 6575 (December 24, 2021): id. 1576, doi:10.1126/science.abf0130.
Herman Pontzer, David A. Raichlen, and Michael D. Sockol, “The Metabolic Cost of Walking in Humans, Chimpanzees, and Early Hominins,” Journal of Human Evolution 56, no. 1 (January 2009): 43–54, doi:10.1016/j.jhevol.2208.09.001.
Chris Organ et al., “Phylogenetic Rate Shifts in Feeding Time during the Evolution of Homo,” Proceedings of the National Academy of Sciences USA 108, no. 35 (August 30, 2011): 14555–14559, doi:10.1073/pnas.1107806108.
Leslie Aiello and Peter Wheeler, “The Expensive-Tissue Hypothesis: The Brain and the Digestive System in Human and Primate Evolution,” Current Anthropology 36, no. 2 (April 1995): 199–221, doi:10.1086/204350.
A young PhD candidate in sociology asked this question of RTB scholars: “When RTB scholars approach their field of truth, are there specific questions...
