Archeologists in southern France have studied bones spanning 8,000 years to reveal how humans caused domestic animals to grow in overall size, while wild animals shrank. Sometimes, environmental factors may cause a species to grow smaller; a century later, the animals' descendants might get bigger again. When humans were introduced into the mix and began rearing certain species, the sizes of wild animals and domesticated ones still developed in roughly the same cycles. "Wild species decreased in body size, while domestic species increased," Allowen Evin, one of the study's authors, told DW. But since they encountered a wealth of information on wild species as well, they expanded their work, resulting in a large-scale comparison.