Capacity for Development: New Solutions to Old Problems

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Either by signing into your account or linking your membership details before your order is placed. Your points will be added to your account once your order is shipped. Click on the cover image above to read some pages of this book! This story is part of Reading Champion, a series carefully linked to book bands to encourage independent reading skills, developed with Dr Sue Bodman and Glen Franklin of UCL Institute of Education IOE Rabbit wakes up to a blanket of snow, but just as he goes out to play he spots a giant snowball Soon Mole and Squirrel join Rabbit in chasing the giant snowball to find out where it's going - and if anyone is inside!

Reading Champion offers independent reading books for children to practise and reinforce their developing reading skills. Fantastic, original stories are accompanied by engaging artwork and a reading activity. Each book has been carefully graded so that it can be matched to a child's reading ability, encouraging reading for pleasure. About the Author A H Benjamin is an established children's author with 30 titles to his credit.

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His books have sold worldwide with more than 20 translations, including Chinese, Korean, Turkish and Arabic. Some of his work has been adapted for radio, television and theatre. He's married with four grown up children and four young grandchildren who have all been his inspiration for writing. He lives in Lincolnshire with wife, Trisha. When he was a little boy he dreamt of being a cowboy He still does! Help Centre. Track My Order. My Wishlist Sign In Join. Benjamin , Andy Rowland.

Earth was a frozen Snowball when animals first evolved

Be the first to write a review. Add to Wishlist. Ships in 7 to 10 business days. Maybe it was the ice itself that drove the evolutionary leap, says Richard Boyle of the University of Southern Denmark in Odense. For Boyle the real puzzle isn't the appearance of multicellular animals. Instead, it's the rise of cellular differentiation — cells with specific roles like liver, muscle and blood. These specialised cells allowed animals to become much more intricate.

It's hard to see how this could have evolved, because specialised cells lose the ability to reproduce on their own. Instead they have to be distinctly self-sacrificing, cooperating with other cells in the body for the greater good of the animal. Only the specialised reproductive cells, the sperm and eggs, get to create a new generation.

By contrast, plants don't just rely on specialist sex cells to reproduce. They can also reproduce themselves from cuttings taken from their stems or roots.

He thinks the severity of Snowball Earth may have pushed animal cells to abandon this flexibility, and specialise. View image of Cells have to work together to make animals Credit: icelight, CC by 2.

BBC - Earth - Earth was a frozen Snowball when animals first evolved

The populations that did survive were often reduced to just a handful of organisms. Boyle suggests that these little groups of survivors were often closely related , encouraging them to cooperate more than usual. Biologists have long known that animals are more likely to help close relatives, because by doing so they can benefit their own genes, which the relative will also carry.

For example, wild animals are likely to adopt orphans that are related to them, but not orphans that are unrelated.

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Boyle thinks that Snowball Earth may have forced cells to behave altruistically. Boyle's notion is controversial and other scientists are sceptical. Butterfield argues that life probably retreated to the open waters of the tropics during Snowball times, but otherwise carried on as normal. View image of The cradle of complex life? It would really help to find some definitive fossils to resolve this. Unfortunately, the fossil record is very patchy in such ancient rocks.

So far, the oldest definitive fossils of complex animals date to around million years ago. That could fit with either hypothesis. Genetics doesn't help much either. By working backwards through the animal family tree and estimating rates of genetic change, scientists have estimated that the first animals are likely to have emerged around million years ago.

But these "molecular clock" estimates are notoriously unreliable. Nonetheless, recent discoveries hint that animal life may have started to gain a foothold during Snowball Earth. In , Malcolm Wallace of the University of Melbourne in Australia discovered strange clumps of fossils in remote regions of Australia and Namibia. In the remains of ancient reefs, Wallace found bubble-shaped fossils up to 3cm across. Many of the bubbles appeared to interconnect into a network of finger-like strands. They date from around million years ago , soon after Earth first became a Snowball.

So Wallace and his colleagues think they may have found the precursors to animals — very early sponge-like creatures, which lived in low-oxygen waters and represented a halfway stage between single-celled microbes and multicellular animals. And they think it is no coincidence that these animal precursors appear right after the first major Snowball glaciation.

Boyle agrees that this kind of primitive animal life may have evolved before the end of Snowball Earth, but he argues that this wasn't the crucial step. Instead, the key threshold is when individual cells forgo their ability to reproduce, and instead take on specific roles within an animal. So far, animals more complex than sponges, with specialised organs that do different jobs, have only been found in rocks laid down after the Snowball. Boyle predicts that they will never be found in older rocks, certainly not in rocks laid down before the Snowball.

Butterfield agrees that such ancient animal fossils may never turn up, but that could simply be because they haven't been preserved.


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He now suspects that Boyle, Planavsky and Wallace have got the whole story backwards. Instead of the ice creating complex animals, he suggests that the first animals appeared million years ago and transformed the planet, cooling the climate.

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View image of Did the first animals somehow freeze the Earth? Credit: Derek Keats, CC by 2. So he thinks the first animals upset the delicate balance of ocean chemistry, with knock-on effects for the rest of the planet. Animals can certainly have big effects on the planet.

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For instance, burrowing animals like worms can break up rocks faster. The resulting rock dust reacts with carbon dioxide in the air, and the minerals produced get washed into the oceans — removing the carbon dioxide from the air. Meanwhile, marine animals boost oxygen levels by eating the remains of dead organisms, which would otherwise consume oxygen.

Butterfield also thinks animals may have driven the evolution of new microscopic plants that sank faster, taking carbon dioxide with them. There is some evidence that the first animals could have thrown Earth into a deep freeze. In , Eli Tziperman of Harvard University in Cambridge, Massachusetts and his colleagues modelled the chemical cycles in the ocean. They found that the evolution of new marine organisms could have helped transport more carbon to the ocean floor and forced a major change in climate.

View image of Ice affects life, and life affects ice Credit: pclvv, CC by 2. Right now there's not enough information to decide whether animals created Snowball Earth, or Snowball Earth triggered animal evolution.