Our early ancestors may have scavenged before they hunted
Dead animals feed a vast crew of vultures, hyenas, beetles, octopuses and even tadpoles, recycling nitrogen and carbon back into ecosystems. Early humans probably joined in: stone tools from the Early Pleistocene look better suited to butchering abandoned carcasses than to hunting, and some modern hunter-gatherers still eat predator kills.
Carrion, from the Latin for meat, is the decaying body of a dead animal, whether it died of disease, was left by a predator or hunter, or was hit by a car. Eating it is called necrophagy. Scavenger is a looser word that also covers animals eating rubbish or dead plants. Decay starts at the moment of death, and bacteria soon release compounds called cadaverine and putrescine, which produce the notorious smell.
The diners are astonishingly varied. Hundreds of invertebrates take part, from burying beetles and blow flies to vulture bees and fire ants. In the sea, octopuses, hermit crabs, starfish and bone-eating zombie worms scavenge, as does a deep-sea amphipod from the Atacama Trench. Among vertebrates, carrion crows, Komodo dragons, wild boars, abyssal grenadier fish and the larvae of midwife toads all feed on remains, and hungry herbivores such as Egyptian mastigure lizards will join in. Apart from some hagfish, only the vultures of the Old and New Worlds are known to depend on carrion to survive.
For hominins such as Homo habilis and Homo erectus, scavenging marrow and meat from large mammals likely supplied some protein and fat; cut marks on bones at several sites support the idea. When hunting took over is unclear, and isotope evidence that Neanderthals were mainly hunters has been disputed. Modern people have eaten zebra and giraffe left by predators, stranded whales and dead livestock, and outbreaks of anthrax and botulism were reported in 1987 and 2002. Unlike vultures and coyotes, humans are highly sensitive to botulinum toxin. Hunter-gatherers who eat carrion reach carcasses quickly, gut them and cook or sun-dry the meat.
Religious law often forbids it: Islam bans animals killed by strangling, falls or goring, and a lost Talmudic list of thirty laws includes a ban too. Some plants and fungi exploit the smell; carrion flowers and stinkhorn mushrooms mimic rotting flesh to recruit insects that spread their pollen or spores.
Source: Carrion
