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The Irish elk (Megaloceros giganteus) lived across Eurasia during the late Pleistocene, roughly four hundred thousand to eight thousand years ago. Despite its common name, the Irish elk was neither native solely to Ireland nor closely related to the modern elk (Cervus canadensis); the name originated from numerous well-preserved Irish elk skeletons discovered in Irish peat bogs. On average, an adult male Irish elk stood about six and a half feet (about two meters) tall at the shoulder, and the largest males had antlers spreading more than twelve feet (about three and a half meters) across and weighing close to ninety pounds (about forty kilograms), the biggest and heaviest known of any deer species.
As for why the Irish elk's antlers became so large, the cause was sexual selection (the process by which certain traits evolve because they increase success in attracting or competing for mates); over many generations, female Irish elk chose to mate with male Irish elk that had the largest antlers, since those antlers signaled strength, health, and dominance. This consistent preference by female Irish elk for males with larger antlers caused males with smaller antlers to reproduce less often, so the genes for larger antlers became increasingly common among their offspring.
Over successive generations, male Irish elk grew antlers that required enormous amounts of energy and nutrients to grow and maintain. When colder climates and reduced vegetation arrived near the end of the last ice age, males could no longer obtain enough food to sustain antler growth, leaving them weakened or starving. As a result, many of those males died before they could reproduce, which meant fewer offspring were born, and over time the population declined until the Irish elk became extinct.
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As for why the Irish elk's antlers became so large, the cause was sexual selection (the process by which certain traits evolve because they increase success in attracting or competing for mates); over many generations, female Irish elk chose to mate with male Irish elk that had the largest antlers, since those antlers signaled strength, health, and dominance. This consistent preference by female Irish elk for males with larger antlers caused males with smaller antlers to reproduce less often, so the genes for larger antlers became increasingly common among their offspring.
Over successive generations, male Irish elk grew antlers that required enormous amounts of energy and nutrients to grow and maintain. When colder climates and reduced vegetation arrived near the end of the last ice age, males could no longer obtain enough food to sustain antler growth, leaving them weakened or starving. As a result, many of those males died before they could reproduce, which meant fewer offspring were born, and over time the population declined until the Irish elk became extinct.
