It ’s been almost 2 million days since the first archaic man ventured out of their African homeland . Exactly whose idea it was to set off on this world turn is difficult to say , yetHomo erectusis generally seen as the most potential campaigner – although a new study may be about to challenge that narrative .
The early bony evidence for the presence of humansoutside of Africawas found beneath a medieval village in Dmanisi , Georgia , in 1991 , yet there ’s still some doubtfulness as to which species the prehistorical remains belong to . Dated to between 1.8 and 1.85 million years ago , the isolated lower jawbone discovered at the site was ab initio identified as a primitive form ofH. erectus , until further discoveries began to muddy the waters .
A total of five skulls – four of which have their jaws attached – have now been recovered and are officially designate asHomo georgicus . Many scholar recall thatH. georgicusis in fact just an other iteration ofH. erectus – which emerge in Africa some 1.9 million year ago before spreading across the globe – while others are less confident .
Five skulls belonging toH. georgicushave been discovered in Dmanisi, but are they really all from the same species?Image credit: tolobalaguer.com/Shutterstock.com
It has also been suggested that the Dmanisi hominids may go toHomo ergaster , although , likeH. georgicus , there is some doubt as to whether this ancient line of descent was aseparate speciesor just another variety ofH. erectus .
To find oneself out who the Dmanisi humans really were , the author of the as - yet un - compeer - brush up field of study conducted phyletic analysis of the remains , thus identifying their position within the genetic family tree diagram of theHomogenus . “ In our phylogenetic analytic thinking , none of the Dmanisi hominins form a baby taxonomic category to eitherH. erectusorH. ergaster , ” spell the investigator .
“ We theorise that the Dmanisi hominins did not share a unparalleled vulgar ancestor withH. erectusorH. ergaster , and we can not support their ascription to either of those metal money , ” they continue .
Moreover , the study authors found that the assemblage at Dmanisi is probably made up of two differenthuman species , one of which they fate asH. georgicuswhile the remaining four skulls symbolize an " unnamed species " . This conclusion is free-base on the fact that the oldest of the five brainpan – which is believed to have belong to a manful individual – has a volume that is around 30 to 33 pct small than the other males in the group , as well as the females .
“ If we assume the Dmanisi hominins comprise a single specie , we have an unexpected situation in which certain grownup male person cranium may be notably smaller than other male cranium and pocket-size than female crania , ” write the study authors . “ This pattern has not hitherto been report in human phylogeny and would need a considerable paradigm shift , ” they say .
weigh up all the possible explanations for this degree of variation , the researchers conclude that “ the most parsimonious hypothesis for the Dmanisi hominins is that two mintage are present among the accumulation . ”
In term of chronology , they approximate that theH. georgicusindividual was credibly present in Dmanisi by around 1.8 million years ago , while the other four specimens accumulated at the site between 1.77 and 1.07 million years ago . More importantly , though , if the researchers ’ theory thatH. georgicuswasn’t directly related toH. erectusstands up to examination , then the interrogation of which human species first left Africa is blown widely capable again .
A preprint of the unpublished study can be found onbioRxiv .
