Historian Andrés Reséndez of University of California, Davis asserts that evidence suggests "slavery has emerged as a major killer" of the indigenous populations of the Caribbean between 1492 and 1550 rather than diseases such as smallpox, influenza and malaria. He posits that unlike the populations of Europe who rebounded following the Black Death, no such rebound occurred for the indigenous populations of the Americas. He concludes that, even though the Spanish were aware of deadly diseases such as smallpox, there is no mention of them in the New World until 1519, meaning perhaps they didn't spread as fast as initially believed, and that unlike Europeans, the indigenous populations were subjected to brutal forced labor in gold and silver mines on a massive scale. Anthropologist Jason Hickel estimates that a third of Arawak workers died every six months from lethal forced labor in these mines.