Did hunting small prey lead to the evolution of big human brains?

Discover how a desperate shortage of ancient elephants and the sudden need to hunt tiny, elusive prey may have forced human brains to rapidly evolve and expand.

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A new study suggests that a dramatic drop in the number of huge animals 200,000 years ago may have driven the evolution of large brains in modern humans. According to journalist James Urquhart, this ecological crisis forced our ancestors to abandon heavy stone tools and adapt to hunting much smaller, faster prey. For over a million years, early human tures used similar kinds of heavy stone tools, such as axes, cleavers, and stone balls. Archaeological evidence shows these tools were ideal for killing and butchering massive plant-eating mammals, known as megaherbivores, which included ancient relatives of elephants, hippopotamuses, and rhinos. However, between 400,000 and 200,000 years ago, a technological shift occurred. Smaller, more sophisticated tools, like sharp blades and precision scrapers, began to appear alongside the traditional heavy tools. Now, Vlad Litov and his colleagues at Tel Aviv University in Israel have found a direct link between this technological change and the sudden decline of large mammals, which were likely decimated by human overhunting. The researchers catalogued archaeological findings from 47 known sites across the Levant, dating from 3.3 million to 12,000 years ago. When they cross-referenced these stone tools with animal remains from each site, an intriguing pattern emerged. The team discovered that around 200,000 years ago, when heavy-duty technologies suddenly disappeared from the record in the Levant, there was also a huge drop in the abundance of megaherbivores heavier than 1,000 kilograms. Meanwhile, the presence of smaller prey increased, along with the number of sophisticated small tools. Interestingly, previous studies show that heavy-duty tools persisted for much longer—until around 50,000 years ago—in other world regions where large prey remained available, such as southern China. Earlier scientific ideas suggested that this technological shift happened simply because humans were already getting smarter and more innovative due to unknown evolutionary pressures or lucky genetic mutations. But Litov and his team support a different idea: the absolute reliance on smaller prey actually drove the evolution of big brains in modern humans. As large animals disappeared, humans had to adapt to hunting smaller animals, which required completely different hunting strategies, more flexible planning, and more complex toolkits. However, not all scientists fully agree. Ceri Shipton at University College London argues that there is more to the story than just prey size. He points out that studies show cognitive change and sophisticated planning were already happening before this period, with evidence of mass hunting of medium-sized animals like horses and bison. Nicolas Teyssandier at the French National Centre for Scientific Research also has reservations. He believes that if humans adapted to new animals, it reflects behavioral adaptation rather than pure intelligence. He argues that it was equally intelligent to design and use heavy-duty technologies for hunting massive megaherbivores. Despite these criticisms, Litov maintains that the shift from large to small prey had a profound effect on humans. From an energetic perspective, a single carcass of an ancient elephant could feed a band of around 35 hunter-gatherers for months. When these high-calorie resources disappeared, turning to smaller animals resulted in lower energy returns per animal. To survive, humans had to acquire dozens of smaller animals, like fallow deer, to compensate for the loss of one elephant. This ecological pressure drove a range of cognitive and behavioral changes, including coordinated hunting of elusive prey, the development of advanced technologies, and increased social cooperation. Ultimately, these heavy demands contributed to the selection for larger brains in later human species, including Neanderthals and Homo sapiens .