Climate Dynamics and the Decline of Elephants and Their Precursors

Elephants and their forebears were pushed into wipeout by waves of extreme global environmental change, rather than overhunting by early humans, according to new research.

The study, published in Nature Ecology & Evolution, challenges claims that early human hunters slaughtered prehistoric elephants, mammoths and mastodonts to extinction over millennia. Instead, its findings indicate the extinction of the last mammoths and mastodonts at the end of the last Ice Age marked the end of progressive climate-driven global decline among elephants over millions of years.

Although elephants today are restricted to just three endangered species in the African and Asian tropics, these are survivors of a once far more diverse and widespread group of giant herbivores, known as the proboscideans, which also include the now completely extinct mastodonts, stegodonts and deinotheres. Only 700,000 years ago, England was home to three types of elephants: two giant species of mammoths and the equally prodigious straight-tusked elephant.

An international group of palaeontologists from the universities of Alcalá, Bristol, and Helsinki, piloted the most detailed analysis to date on the rise and fall of elephants and their predecessors, which examined how 185 different species adapted, spanning 60 million years of evolution that began in North Africa. To probe into this rich evolutionary history, the team surveyed museum fossil collections across the globe, from London’s Natural History Museum to Moscow’s Paleontological Institute. By investigating traits such as body size, skull shape and the chewing surface of their teeth, the team discovered that all proboscideans fell within one of eight sets of adaptive strategies.

“Remarkably for 30 million years, the entire first half of proboscidean evolution, only two of the eight groups evolved,” said Dr Zhang Hanwen, study coauthor and Honorary Research Associate at the University of Bristol’s School of Earth Sciences.

“Most proboscideans over this time were nondescript herbivores ranging from the size of a pug to that of a boar. A few species got as big as a hippo, yet these lineages were evolutionary dead-ends. They all bore little resemblance to elephants.”

The course of proboscidean evolution changed dramatically some 20 million years ago, as the Afro-Arabian plate collided into the Eurasian continent. Arabia provided crucial migration corridor for the diversifying mastodont-grade species to explore new habitats in Eurasia, and then into North America via the Bering Land Bridge.

“The immediate impact of proboscidean dispersals beyond Africa was quantified for the very first time in our study,” said lead author Dr Juan Cantalapiedra, Senior Research Fellow at the University of Alcalá in Spain.

“Those archaic North African species were slow-evolving with little diversification, yet we calculated that once out of Africa proboscideans evolved 25 times faster, giving rise to a myriad of disparate forms, whose specialisations permitted niche partition between several proboscidean species in the same habitats. One case in point being the massive, flattened lower tusks of the ‘shovel-tuskers’. Such coexistence of giant herbivores was unlike anything in today’s ecosystems.”

By 3 million years ago the elephants and stegodonts of Africa and eastern Asia seemingly emerged victorious in this unremitting evolutionary ratchet. However, environmental disruption connected to the coming Ice Ages hit them hard, with surviving species forced to adapt to the new, more austere habitats. The most extreme example was the woolly mammoth, with thick, shaggy hair and big tusks for retrieving vegetation covered under thick snow.

The team’s analyses identified final proboscidean extinction peaks starting at around 2.4 million years ago, 160,000 and 75,000 years ago for Africa, Eurasia and the Americas, respectively.

“It is important to note that these ages do not demarcate the precise timing of extinctions, but rather indicate the points in time at which proboscideans on the respective continents became subject to higher extinction risk,” said Dr Cantalapiedra.

Unexpectedly, the results do not correlate with the expansion of early humans and their enhanced capabilities to hunt down megaherbivores.

Sources: University of Bristol

Venus Figurines

Figurines of women carved or sculpted from stone, ivory, or clay are a type of Paleolithic art found widely across Europe. These figurines share many striking similarities. While details such as facial features and feet are largely ignored, feminine sexual characteristics (breasts, belly, hips, thighs, and vulva) are often exaggerated. The focus on features related to sexuality and fertility, and the round body shapes depicted (during the Ice Age fat would have been a precious commodity) suggest that the figurines may have played a symbolic role as a charm relating to childbirth or, more generally, fertility.

Some researchers believe that the figures represent a “mother goddess,” but there is no real evidence for such an interpretation. Others have focused instead on the fact that the figurines demonstrate widely shared cultural ideas and symbols. These would have been crucial to social interactions and exchanges of resources, information, and potential marriage partners in the Ice Age world.

Stone Tools Used By Homo Erectus Discovered

Archaeologists have discovered hundreds of stone tools in a goldmine where Homo erectus would have inhabited 700,000 years ago in the eastern part of the Sahara Desert, 70 km east of the modern city of Atbara in Sudan.

Homo erectus (meaning “upright man”) is an extinct species of archaic human from the Pleistocene, with its earliest occurrence about 2 million years ago. Studies of surviving fossils suggest that the species had a humanlike gait and body proportions, and was the first human species to have exhibited a flat face, prominent nose, and possibly sparse body hair coverage.

A gold rush in the eastern Sahara Desert has led to many open-cast mines being excavated in search of the valuable ore. The mining activity has allowed archaeologists to study exposed layers containing large tools with a transverse cutting edge, and almond-shaped cleaver tools with chamfered edges on both sides, which form a pointed tip at the junction.

Archaeologists believe that the site was a workshop for the manufacturing of stone tools, evident by the discovery of associated flakes formed during their production.

Layers of earth and sand lying just above the tools have been analysed using optically stimulated luminescence (OSL), which dates the earthen-sand layer to around 390 thousand years ago.

Professor Mirosław Masojć from the Institute of Archaeology of the University of Wrocław said: “This means that the layers below are certainly older. Based on the style of workmanship of the tools, I believe that they may be over 700,000 years old, and perhaps even a million years old – similar to their counterparts in South Africa”.

The researchers suggest that the site is the oldest known example of tool manufacturing within the areas of Egypt and the Sudan that has a well-confirmed chronology, in which Masojć adds: “Yes, ancient tools are found in deserts, but never before have they come from layers that we can safely determine their age”.

Source: HeritageDaily

The Extinction Of Ice Age Mammals May Have Forced Humans To Invent Civilization

Why did we take so long to invent civilization? Modern Homo sapiens first evolved roughly 250,000 to 350,000 years ago. But initial steps towards civilization, harvesting, then domestication of crop plant, began only around 10,000 years ago, with the first civilizations appearing 6,400 years ago.

For 95% of our species’ history, we didn’t farm, create large settlements or complex political hierarchies. We lived in small, nomadic bands, hunting and gathering. Then, something changed.

We transitioned from hunter-gatherer life to plant harvesting, then cultivation and, finally, cities. Strikingly, this transition happened only after the ice age megafauna—mammoths, giant ground sloths, giant deer and horses—disappeared. The reasons humans began farming still remain unclear, but the disappearance of the animals we depended on for food may have forced our culture to evolve.

Early humans were smart enough to farm. All groups of modern humans have similar levels of intelligence, suggesting our cognitive capabilities evolved before these populations separated around 300,000 years ago, then changed little afterwards. If our ancestors didn’t grow plants, it’s not that they weren’t clever enough. Something in the environment prevented them—or they simply didn’t need to.

Agriculture has significant disadvantages compared to foraging. Farming takes more effort and offers less leisure time and an inferior diet. If hunters are hungry in the morning, they can have food on the fire at night. Farming requires hard work today to produce food months later—or not at all. It requires storage and management of temporary food surpluses to feed people year round.