The Ultimate Guide to Ancient Life on Earth

The Ultimate Guide to Ancient Life on Earth

The Ultimate Guide to Ancient Life
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This BBC Science Focus special edition reveals the story of how ancient life developed on Earth from the very first lifeforms through to the evolution of humans... IN THIS ISSUE - Why life on Earth wasn't an accident - What T. rex really looked like - Piecing together our hominin family tree - How walking whales returned to the water - The surprising truth about Neanderthals - Missing links: dino-birds and dino-bats

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Immediate Media Company London Limited
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1 min.
the social brain

Around 200,000 years ago, our Homo sapien ancestors were one of a number of hominin species spread out across the globe. Yet Homo sapiens are the only species alive today. How we survived where others didn’t is a complex tale with many different storylines and characters. But eventually Homo sapiens gained the upper hand – although all non-Africans carry about two per cent Neanderthal DNA, revealing that our ancestors interbred with our stockier cousins. Why we survived and Neanderthals died out is still controversial. Some academics think that our ancestors outcompeted Neanderthals by being smarter – and that our impressive ‘social brains’ gave us the advantage. Humans can live in groups of 150 to 200 people, while the maximum for chimpanzees is around 50. If that figure doubles, tensions develop within…

1 min.
the history of life on earth

Our Solar System began to develop 4.6 billion years ago from a spinning disk of material. Around 50 million years later, Earth is thought to have collided with another planet (Theia), hurling out debris, some of which stuck together to become the Moon. The gravitational pull of our lunar neighbour helped to stabilise Earth’s rotation and get the planet’s climate under control. The first continents and oceans began to form 4,400 million years ago. None of Earth’s original crust remains today, but we’ve found a few crystals of it in Western Australia. The chemistry of these crystals, known as zircons, reveals that by this time Earth had oceans of water – crucial for life. As Earth cooled around 4,000 million years ago, scientists think that the mantle began to move in predictable…

1 min.
how fossils form

1. DEATH Fossils form best in environments without much oxygen that keep out bacteria, such as a stagnant lake or cold sea. These conditions also encourage the chemical reactions that replace the body’s so! tissues with hard minerals. 2. QUICK BURIAL A layer of sediment stops animals from nibbling the "esh and protects the skeleton from being scaftered by ocean currents. Shallow seas are good because a constant, gentle rain of dead plankton and sediment is washed down by rivers. And the quicker the burial the better. Sediments turn to rock around the fossil over millions of years. 3. EROSION The motion of Earth’s tectonic plates lifts the fossil above sea level, so erosion can start peeling away the layers of rock above.…

11 min.
the origin of life

THE ORIGIN OF LIFE – HOW LONG AGO WAS THAT? Around four billion years ago, when the Earth was still partially molten and under heavy bombardment from meteors, the very first life-like systems appeared. Somehow, chemicals developed life-like properties – using matter and energy from the hellish environment to make more of themselves. Origin of life researchers are still trying to work out exactly how, during this period, chemistry suddenly became biology. Once basic biological systems formed, life never looked back – evolving into the two enormously diverse groups of microbes now known as bacteria and archaea. A merger between two of these ancient cell types, billions of years later, is thought to have given rise to more complex, multicellular organisms – including us, and all the plants, fungi and animals that…

1 min.
jargon buster

ABIOGENESIS The technical term for life originating from non-living matter such as simple organic chemicals. The opposite, biogenesis, means living matter arising from other living matter, which is how life on Earth proliferated once it started. RNA WORLD RNA is like a single-stranded version of DNA and performs many important functions in all living cells. Scientists have shown that RNA can spontaneously form a self-replicating molecule, suggesting the Earth was once populated by simple self-replicating RNA forms. PROTON GRADIENT Cells can only function properly with energy created by complex metabolic reactions, which generate a di"erence in chemical charges in di"erent parts of the cell. This is known as a proton gradient. Working out how it could occur spontaneously is a key part of establishing how early life functioned. LUCA The Last Universal Common Ancestor is the ancient…

7 min.
the physics theory of the origin of life

From the expansion of the Universe to the motions of the tiniest subatomic particles, modern-day physics can help us interpret a dizzying number of natural phenomena. But can it explain how life as we know it begin? Dr Jeremy England, assistant professor of physics at the Massachusetts Institute of Technology (MIT), thinks it can. He is currently working on a bold theory that hopes to reveal how life-like behaviours could emerge from an inert collection of chemicals. “I was always interested in how the physics of big, messy assemblies of particles becomes life-like, ever since I was doing research on protein folding as an undergraduate,” says England. “It was the way I could successfully refuse to choose between theoretical physics and biology – both were fascinating to me.” England’s work is based…