Researchers have found a nearly 164,000-year-old molar from a member of the archaic human species known as Denisovans in a cave in Laos, suggesting that Denisovans lived in a wider range of environments than indicated by earlier evidence. Before the discovery, Denisovans were thought to have lived only at high altitudes in relatively cold climates in what are now Russia and China, but the discovery of the tooth in Laos suggests that they may have lived at low altitudes in relatively warm climates in Southeast Asia as well.

Which choice best states the function of the underlined portion in the text as a whole?