Excerpt from esbtrib.com
It is very interesting to know how, we, humans developed from our ancient forms into our present state today. Of how great that transformation would have been. If only there are answers that can satisfy our thirst for facts on how we really evolved.
Until today, one of the most prevailing theories about our evolution claimed that our genus, Homo, had evolved from smaller early humans who, eventually, became taller, heavier and longer-legged. This process in progression resulted in Homo erectus, who migrated out of Africa and colonized Eurasia.
While we know that small-bodied H. erectus, in average measured less than 5 feet tall and weighed below 50 kilograms and were living in southern Europe at about 1.77 million years ago, the origin of the larger body size associated with modern humans has been evasive.
The fewness or scarcity of the knowledge about the origin of larger members of the Homo genus is basically the outcome of the lack of evidence. Prior estimates of body size had been based on well-preserved specimens which were easy to assign a species to.
Considering the rarity and the inequality of these samples both in terms of space and time, little is known about the geographical and chronological variation in the body sizes of the early Homo.
The Universities of Cambridge and Tübingen conducted a joint study and the result showed that increases in body size occurred thousands of years after H. erectus left Africa; this growth in Homo body sizes primarily took place in the Koobi Fora region in modern Kenya.
Manuel Will, co-author of the study which has been published in the Journal of Human Evolution, then concluded that, “The evolution of larger bodies and longer legs can thus no longer be assumed to be the main driving factor behind the earliest excursions of our genus to Eurasia.
The team were able to estimate our earliest ancestors’ height and body mass by using tiny fragments of fossil. Their findings, rather surprisingly, indicate a huge diversity in body size; this is particularly surprising for the obvious reason that the wide variation we see in humans today is thought to be a relatively recent development.
Dr Jay Stock, co-author of the study, in a statement said, “If someone would ask you ‘are modern humans 6 foot tall and weigh 70kg?’ you’d probably answer,‘well some are, but many people are not,’ so what we’re starting to show is that this diversification happened really early in human evolution.”
Stock and Will, both co-authors of the study, are the first scientists in 2 decades to compare the body size of humans from between 1.5 and 2.5 million years ago. They are also the first to use fragmentary fossils – many as small as toes, none longer than 5cm – to estimate body sizes.
The researchers have also revealed substantial regional variation in the size of early humans by comparing measurements of fossils from sites in Kenya, Tanzania, South Africa and Georgia. Those groups who lived in South African caves, for example, were 4.8 feet tall on average. Some of the skeletons found in Kenya’s Koobi Fora region would have stood nearly 6 feet tall, a height comparable to the average height of modern British males.
In addition, Stock said,“Basically every textbook on human evolution gives the perspective that one lineage of humans evolved larger bodies before spreading beyond Africa. But the evidence for this story about our origins and the dispersal out of Africa is just no longer fitting.
It is apparent that Stock and Will have rewritten the history of the development of early humans; diversity has deep roots amongst the Homo genus.