How to Elucidate Functional Genomic Differences between Extinct Organisms and Their Extant Relatives

BACKGROUND On October 3,2022,Svante Pääbo,a Swedish evolution-ary geneticist,was awarded the Nobel Prize in Physiology and Medicine.This breaking news brought paleogenomics,the in-terdisciplinary field of geology and biology,to the forefront of public attention.By sequencing the genomes of the extinct Ne-anderthal and Denisovan,Prof.Pääbo and his research team found that ancient gene flow events did happen between these extinct ancient humans and the ancestors of Homo sapiens(Prüfer et al.,2017,2014;Fu et al.,2016;Meyer et al.,2012),which paved the way for the academic community for a new understanding of human evolutionary history.Similar to the ge-netic contribution of extinct humans to anatomically modern humans,it has been proved that several extinct animal species or populations also have genetic components existing in the ge-nomes of living organisms(Sheng et al.,2019;Barlow et al.,2018).For example,the extinct straight-tusked elephant was a product of multiple hybridizations of three different elephant species,namely the ancestor of African elephant,Mammoth and African forest elephant(Palkopoulou et al.,2018).From this perspective,interspecific hybridization among mammals is a common phenomenon in their evolutionary history.