world and chimpanzees , two very closely related species , partake a commonape - comparable ancestorthat lived on Earth meg of year ago . But when did this ancestor begin to deviate genetically , break open into the dissimilar lineages that would eventually give ascent to these two species ?

Previous approximation using the dodo criminal record advise that the last common root of world and chimps last around6 - 7million year ago , which has been widely accepted by the scientific community of interests . However , a Modern subject field may gainsay this as the finding propose that the unwashed antecedent could have begun diverging as far back as13 million yearsago . The news report has been publish inScience .

Chimpanzees are our snug living transmissible relatives ; our deoxyribonucleic acid is around99 % exchangeable . Comparing the DNA of these two species can therefore unearth clue about their evolutionary history . By find the mutation rates of both species , which attend to asevolutionary “ clocks ” , it is possible to define when they last shared a vulgar ancestor .

Earlier estimates suggest that the most late vulgar ancestor of human beings and chimps endure around 6 - 7 million yr ago ; however , recent evidence has suggested that the mutant rate may have been immensely overestimated and that the most late common ancestor ( MRCA ) in fact lived12 million year ago . Now , a fresh study investigating the chromosomal mutation rates of chimpanzee has provided further grounds to support this whim , hint that the MRCA lived around 13 million years ago .

“ Our results impart substance to the idea that the human - chimp split was considerably older than has been recently thought , ” study carbon monoxide - author Gil McVean toldLive Science .

The averagemutation rateof homo is approximately one mutation per two billion base pairs of DNA per year . for investigate whether Pan troglodytes go through alike rates , the research team sequenced the genomes of nineWestern chimpanzees ; two fathers , two mother , and five of their offspring .

The researchers found that human and chimpanzees divvy up very exchangeable mutation rates and from this data the squad were then able to reckon divergence rates . “ Our event betoken that human and chimp ancestor ’ genomes would depart by about 0.1 pct every million years , so when we see a disagreement of 1.2 percent , we generalize that it must have been about 12 million class – 13 million years is our actual estimate , ” McVean toldLive Science .

However , as paleoanthropologist John Hawkspointed out , this estimation is only the middling time for disagreement and it is therefore still possible for the rip to have come about around 7 million year ago if the ancestral universe was very large . This is because a large universe would bring home the bacon copious opportunity for the gene pool to begin diversifying well in advance of the actual snag .

While the squad detect that human being and chimps deal similar rates of chromosomal mutation , they see that Male contributedseven to eighttimes the telephone number of mutations to issue than female person . In humanity , however , males contribute only three to four times as many as females .

Males pass on more mutations to offspring than females because male constantly produce spermatozoon throughout their lives . As a cell watershed , there is a fortune that a mistake will be made during DNA replication which could give ascension to a mutation if it is not fix by cellular mental process . Females , however , are born with a finite number of eggs that do not divide and are therefore less potential to go through mutation .

Another interestingfindingwas that male chimps give three further mutation to offspring with every year of the father ’s historic period , whereas virile humans contribute only two more per year . So what is causing these differences in mutation rates and patterns between these two very nearly related to mintage ? The scientists believe it could be down to sex .

Chimpanzees are ahighly promiscuousspecies ; far more wanton than humans . therefore , they have evolve a rather telling pair of ball to keep up with all of the sperm that is necessitate for hatful of pairing . Relative to physical structure size , the bollock of a male chimpanzee are ten sentence big than the bollock of a male human . While all this spare spermatozoan might be great for the females , it unfortunately increase the likelihood of mutations arise .

While the subject field size was modest , the finding are important nonetheless and seem to add to the grow organic structure of evidence that the ancestors of mankind and chimpanzee may have begun depart long before earlier estimates .

[ ViaScience , LiveScienceandNational Geographic ]