The endurance running hypothesis and hunting and scavenging in savanna-woodlands

1. What they did

Bramble and Lieberman (2004) proposed that long-distance endurance running (ER) evolved in early Homo about 2 million years ago, partly because it helped them get meat, marrow and brains by hunting animals to exhaustion (persistence hunting) and by racing other scavengers to carcasses. Pickering and Bunn, who study meat eating by early humans, test this idea against what is known about the habitats and ecology of early Homo.

They draw on reconstructions of early Homo environments (savanna-woodlands, about 2.3 to 1.5 million years old), the archaeological record of bones and tools, studies of scavenging opportunities, Liebenberg’s (2006) observations of persistence hunting in the central Kalahari, and their own observations of Hadza hunters in Tanzania (over twenty years) and Kua San hunters in the east-central Kalahari.

2. What they found

Hunting with endurance running needs tracking

• Hoofed animals (ungulates) dominate the bones at early Homo sites, and they can sprint faster than humans. So a hunter running an animal down, or chasing a wounded animal, would lose sight of it and would need to track it. The authors define tracking as following a prey animal without seeing it.
• Following a fresh blood trail is far easier than finding and reading other spoor such as footprints, saliva, dung, urine or hair. But there is no evidence that early Homo had projectile weapons that could wound an animal: wooden spears appear only about 400,000 years ago, and stone points only after about 40,000 years ago.
• Quoting Liebenberg (1990), tracking in savanna-woodland demands high intellectual ability and probably first developed where tracking is easiest: deserts and snow. Early Homo lived in savanna-woodlands, where compact soil and vegetation make tracking harder, and where persistence hunting is also harder than in hot, sandy places.

Persistence hunting is rare

• Running hunts are known only from very open, very hot places such as the central Kalahari, parts of the American Southwest and inland Australia. Running an animal across loose or wet sand tires them more than running across firmer woodland soils.
• In twenty years watching well over 100 successful Hadza bow-and-arrow hunts, and many more unsuccessful hunting and scavenging attempts, the authors never saw persistence hunting, and Hadza informants did not describe it. The Hadza often give up a blood trail that heads into thick vegetation and collect honey instead.
• In Liebenberg’s 20 years of observations, only two persistence hunts were spontaneous (both successful, both by the same four hunters). Eight more were prompted for filming; only three of those succeeded, even though they started from a vehicle and the hunters refilled water bottles.

A walking hunt

Among the Kua San, hot dry-season hunting by walking, not running, works. Bush duiker are the most common prey, then steenbok, and sometimes large antelope such as greater kudu. On one successful hunt, the hunter, carrying only a digging stick, found the fresh hoof prints of a duiker and followed the trail at a steady walk for about three hours, pushing the duiker from one shade tree to the next. Under each tree the ground was covered in tracks of many duiker, so he circled the shade and picked out the tracks of his duiker leaving. When the tired duiker was first seen, about 250 m ahead and running across his path, he did not head towards it but kept to the trail. He found it standing exhausted under trees, head low and tongue out, clubbed it and carried it to camp. Hunters usually rested in camp the day after a walking hunt.

Scavenging with endurance running

• The ER idea assumes early scavenging was a race against other scavengers. But studies of modern savannas show that riparian woodland (along rivers) is a low-competition zone: carcasses are harder for carnivores and vultures to see there and last longer, and most African carnivores are built for open country.
• Cutmarks on the meaty middle sections of limb bones suggest early Homo reached carcasses before other carnivores. Hadza get about 20% of their carcasses by driving predators off kills, without dedicated running; they run more often to avoid rain, bees and elephants.
• Bone assemblages formed largely without carnivore input, suggesting low competition. The prime-adult prey at FLK Zinjanthropus (Olduvai Gorge) does not fit scavenging from running predators or hunting as a running predator, both of which would select young, old and sick animals.

3. What they concluded

• The authors agree that early Homo needed a high-quality diet with plenty of meat and was a capable carcass forager.
• They doubt that early Homo regularly and successfully used endurance running to hunt or scavenge, and they are reluctant to credit early Homo with the impressive tracking skills of the Kalahari San while early human thinking and foraging abilities are still being researched.
• What drove the evolution of endurance running is unclear, but hunting and scavenging probably contributed little, if anything.

4. How tracking was or was not used

The paper is about tracking: whether early humans could have tracked prey well enough to make running hunts work. The authors describe Hadza following blood trails of animals shot with poisoned arrows (and abandoning them in heavy vegetation), and a Kua San hunter trailing a duiker by its hoof prints for about three hours, including picking out one animal’s tracks among many under shade trees. They argue that persistence hunting needs “truly phenomenal tracking skills” when walking, and even greater skills when running.

5. Tracker or observer certification

Not reported. The hunters are described as skilled trackers from long observation, but no test or certification of their skill is reported.