When anthropologists imagine the environments in which humanity ’s ancestors evolved , they incline to think of either the forest or grasslands that dominate Africa today . However , an overview of Africa ’s fogey record indicates things were much different 7 million , or even 1 million , age ago than we usually recognise . We evolved in surroundings with more jumbo animate being than we see today .
Dr Tyler Faithof the University of Utah analyse the collected fogey records for East African herbivore over the last 7 million yr , taking in 305 fossil communities . Until 700,000 years ago , almost all of these were outside the limit of what we see today , with a much greater frequency of so - called megaherbivores weigh more than a metric ton .
Even before cattle produce , the grasslands of Africa were dominate by ruminant such as wildebeests and giraffe . One elephant may eat as much as many antelope , but doing so along with other large non - ruminant herbivore , such as rhinoceroses , is relatively rare . When it come to intellectual nourishment informant for carnivores , or droppings yield to fertilize the soil , it is the ruminant that mould the continent .
However , religion and colleagues show in theProceedings of the National Academy of Sciencesthat this was n’t true until around a million year ago , followed by a changeover last some 300,000 age .
Before that time , there were many more megaherbivore coinage and fewer wight press 18 - 80 kg ( 40 - 180 quid ) . Unsurprisingly , this also signify more giving carnivores . Today , the remain megaherbivores need fear only lion and man , but Africa used to also support gargantuan hyenas , saber - toothed cats , and preponderantly carnivorous bear . Although there were also swings in the richness of medium - sized animal , and in whether they preferred grasses or leaves , over the same period , these broadly speaking go on within modernistic ranges .
It is easy to jump to the finis mankind are responsible for the disappearance of these fantastic beasts . After all , on other continent and islands , humanity ’s appearance has beenbad newsfor the largest animate being . However , the story is not so wide-eyed in Africa .
Ecosystems similar to the one we see today in East Africa come forth hundreds of yard of geezerhood before modern humans . The species that play our direct antecedent around 700,000 years ago when the variety make position may have had most of our intelligence , but their tools were far less advanced and flux with their small number probably had minuscule to do with the megaherbivores ' downslope .
alternatively , Faith and conscientious objector - generator believe progressively dry mood time interval , combined withC4 grassesdisplacing C3 , shift the advantage to more drought - tolerant ruminants . This sent ripples through the food vane that convert Africa ’s ecosystem and in all likelihood have some of the behavioral and technological changes that made us what we are today .
