which

"That has led to countless variations on models being proposed to explain these differences. What we have shown here is that all the different curves are in fact the same exact curve, just stretched and shifted over different temperatures. And what's more, we have shown that the optimal temperature and the critical maximum temperature at which death occurs are inextricably linked."

"Whatever the species, it simply must have a smaller temperature range at which life is viable once temperatures shift above the optimum."

Senior author, Dr. Nicholas Payne, from Trinity's School of Natural Sciences, added: "These results have sprung forward from an in-depth analysis of over 2,500 different thermal performance curves, which comprise a tremendous variety of different performance measures for a similarly tremendous variety of different species -- from bacteria to plants, and from lizards to insects."

Their work uncovered traces of two disease-causing pathogens -- those behind paratyphoid fever and relapsing fever -- which match the symptoms described in eyewitness records from that time.

"In most ancient human remains, pathogen DNA is extremely fragmented and only present in very low quantities, which makes it very difficult to obtain whole genomes. So we need methods capable of unambiguously identifying infectious agents from these weak signals, and sometimes even pinpointing lineages, to explore the pathogenic diversity of the past," he adds.