Washington: A fatty diet provided human ancestors with the nutrition to develop bigger brains, long before they began hunting large mammals for meat, according to a study. The research challenges the widely held view among anthropologists that eating meat was the critical factor in setting the stage for the evolution of humans.
The study found that our early ancestors acquired a taste for fat by eating marrow scavenged from the skeletal remains of large animals that had been killed and eaten by other predators. “Our ancestors likely began acquiring a taste for fat four million years ago, which explains why we crave it today,” said Jessica Thompson, an anthropologist at Yale University in the US.
“The reservoirs of fat in the long bones of carcasses were a huge calorie package on a calorie-poor landscape. That could have been what gave an ancestral population the advantage it needed to set off the chain of human evolution,” said Thompson, who completed the research as faculty at Emory University in the US.
While focusing on fat over meat may seem like a subtle distinction, the difference is significant, Thompson said. The nutrients of meat and fat are different, as are the technologies required to access them. Meat eating is traditionally paired with the manufacture of sharp, flaked-stone tools, while obtaining fat-rich marrow only required smashing bones with a rock, Thompson noted.
The study reviewed evidence that a craving for marrow could have fuelled not just a growing brain size, but the quest to go beyond smashing bones with rocks to make more sophisticated tools and to hunt large animals. The human brain consumes 20 per cent of the body’s energy at rest, or twice that of the brains of other primates, which are almost exclusively vegetarian.