Education-Science

'Dragon teeth’ reveal ancient ape’s place in primate family tree

Science Mag 11/13/2019

In 1935, anthropologist Gustav von Koenigswald came across several strange teeth in drug stores in Hong Kong and southern China. The specimens, sold as “dragon teeth,” to be ground up for use in Chinese medicine, were special: They were apelike, but huge—much bigger than the molars of any other fossil or living primates. Their size (and that of four fossilized jaw bones) suggested that Gigantopithecus blacki was the largest primate ever discovered, towering nearly 3 meters in height(9 feet). But without any skulls or skeletons, researchers didn’t know whether the animal, which lived from roughly 2 million to 200,000 years ago, was a relative of today’s orangutans, today’s African apes, or something else entirely.

Frido Welker, an evolutionary geneticist at the University of Copenhagen, and his colleagues set out to examine G. blacki teeth for intact pieces of proteins called peptides, which may be preserved for up to a few million years—far longer than more fragile DNA. Welker and his colleagues dissolved tiny amounts of enamel from a G. blacki molar and used mass spectrometry to identify more than 500 peptides that matched six proteins. By comparing the amino acids to those in the same six proteins in living apes, including orangutans, gorillas, and other apes and monkeys, they calculated that the giant ape was most closely related to orangutans. The two lineages probably split off between 10 million and 12 million years ago, they report today in Nature.

Is Evolution Predictable? Important Implications for the Way We Understand Life on Earth

SciTech Daily 11/15/2109

“Our team is the first to report that although evolution of similar color patterns in Heliconius may be driven by similar forces–like predators avoiding a particular kind of butterfly–the pathway to that outcome is not predictable,” said Carolina Concha, lead author of the paper and a post-doctoral fellow at STRI. “This really surprised us because it reveals the importance of history and chance in shaping the genetic pathways leading to butterfly wing-pattern mimicry.”

Heliconius‘ bright wing colors signal to bird predators that the butterflies are toxic. Flashy male wing patterns signal to females that they are choosing the right species to mate with. Somehow these two forces, predation and mating, lead to similar wing patterns in groups of butterflies isolated in the mountain valleys and foothills of the Andes. By knocking out a single gene called WntA in 12 different species and their variants, the molecular biologists on the team could tell whether the butterflies in a pair with the same wing patterns were using the same genetic pathways to color and pattern their wings. They were not.