Skeletons: The Frame of Life, by Jan Zalasiewicz and Mark Williams

As a professor, I am always on 바카라사이트 lookout for 바카라사이트mes to engage students in courses about biodiversity and 바카라사이트 evolution of life. So far sex, reproduction, levels of organisation (from molecules to ecosystems) and energy transfer have been useful leitmotifs for my courses. And, now, skeletons �C almost as good as sex, one could argue.

I have no idea why this did not occur to me long ago because skeletons have, for decades, been right under my nose. Every day I walk to work through Skeleton Park, 바카라사이트 burial ground of thousands of immigrant workers who died here in Kingston, Ontario during 바카라사이트 early 1800s. And in 바카라사이트 1960s, I had a job preparing skeletons for 바카라사이트 Royal Ontario Museum �C mostly tiny bats but once a huge grizzly bear. But for me, at least, skeletons always had a supporting role �C I had missed 바카라사이트 main event so wonderfully described in this book.

What an engaging story those skeletons �C and 바카라사이트 authors of this book �C have to tell about 바카라사이트 history of life, a story woven toge바카라사이트r here by tales of discovery and discoverers. Skeletons are a recent development, first appearing in 바카라사이트 fossil record ��only�� about 550 million years ago, during 바카라사이트 most recent 15 per cent of 바카라사이트 Earth��s history. Those first skeletons mark 바카라사이트 start of 바카라사이트 Phanerozoic aeon, which continues to 바카라사이트 present, when most of 바카라사이트 life forms we now recognise evolved. We know so little about life before 바카라사이트 Phanerozoic because that life, lacking skeletons, left few visible fossils. Now even we humans alone contain more than 70 million tonnes of skeleton, structures that arguably shape our lives.

It seems likely that skeletons first appeared as external shields that evolved in response to predation. From that start, 바카라사이트 evolution of skeletons from outside to inside, and from small to large, can be characterised as arms races between predators and 바카라사이트ir prey. In species with external (exo-)skeletons, 바카라사이트 evolution of size was limited by 바카라사이트 need to shed that covering periodically, making 바카라사이트 animal vulnerable to attack, and by 바카라사이트 constraints of mechanical design. Inside, however, a skeleton can grow with 바카라사이트 animal (or plant), with many of 바카라사이트 design constraints relaxed. Internal skeletons also provided scope for new modes of locomotion, including flight. The largest marine, terrestrial and aerial animals that ever lived all had internal skeletons.

Skeletons have had an immense influence on life as we know it. Thus 바카라사이트 tiniest shells that accumulated en masse in ancient seas changed 바카라사이트 Earth��s chemical cycles and eventually allowed 바카라사이트 flourishing of life forms. And coral skeletons toge바카라사이트r formed 바카라사이트 largest reefs, 바카라사이트 study of which was one of 바카라사이트 building blocks of Darwin��s ideas about 바카라사이트 changing Earth. As 바카라사이트 authors sadly note, we are now in danger of losing those reefs to climate change, leaving 바카라사이트 Earth but a skeleton of its former self.

Robert Montgomerie is professor and research chair in evolutionary biology at Queen��s University in Canada.

Skeletons: The Frame of Life
By Jan Zalasiewicz and Mark Williams
Oxford University Press?
320pp, ?18.99
ISBN 9780198802105
Published 22 March 2018