history of life a very short introduction

[...]... waters, if, for example, there is a dramatic growth of algae and other floating plants at the surface, a so-called algal bloom These occur in warm conditions, and the lakes and oceans may become temporarily stagnant The stagnation of the waters may itself kill swimming creatures, and beasts that crawl around on the bottom muds The lack of oxygen can also mean that the normal 5 Introduction Equally famous... measurements of the proportions of parent to daughter element in a suitable rock sample could then give an estimate of the age of the rock Aeon Era Period Quaternary Cenozoic Tertiary Neogene Palaeogene Cretaceous Phanerozoic Mesozoic Jurassic Triassic Permian Pennsylvanian Carboniferous Mississippian Devonian Palaeozoic Silurian Ordovician Precambrian Cambrian Proterozoic Archaean Hadean 3 Geological timescale... claim is still much debated Traces of early life In 1996, Stephen Mojzsis, then a graduate student at the Scripps Institution of Oceanography at La Jolla, California, made a startling announcement in the journal Nature He claimed to have identified a clear chemical signature for life in carbon compounds from Isua Group rocks He had analysed minute grains of graphite, a form of carbon, in the rocks, and... relationships of humans and apes, and showed that our nearest relative was the chimpanzee, then the gorilla, and then the orang-utan This was not so unexpected, and it agreed with the pattern of relationships established from studies of anatomy The shocking part of the paper was that the molecular clock said humans and chimps had diverged only 5 million years ago 9 Introduction Zuckerkandl and Pauling... systematists had attempted to draw up trees of relationships based on a judicious sifting of the character evidence A biological character is any observable feature of an organism – ‘possession of feathers’, ‘possession of four fingers’, 11 Introduction I remember when I attended my first scientific meeting, as an undergraduate, a session of the Society for Vertebrate Palaeontology and Comparative Anatomy at... 400-million-year-old trilobite or a 200-million-year-old ammonite, are actually largely made from the original calcium carbonate of their external skeleton or shell, as in life Similarly, by far the majority of dinosaur bones are still made of the original calcium phosphate (apatite), the main mineralized constituent of bone then and today If you look closely at the outer surface of these fossils, perhaps with a. .. burnt off Life is based on carbon, hydrogen, and oxygen, and these all remain in a gaseous state at high temperatures Of course water boils at 100 ◦ C, and life is essentially water (H2 O) with carbon The Sun and its accompanying planets formed some 4.6 billion years ago from gas into which earlier generations of stars had spewed not only hydrogen and helium but small amounts of 20 As the Earth’s surface... opportunity Introduction The Age of Reptiles ended because it had gone on long enough and it was all a mistake in the first place Will Cuppy, How to become extinct (1941) It is hard to make sense of the history of life on Earth A mass of strange and extraordinary animals and plants perhaps flits before our eyes when we think of prehistory: Neanderthal man, mammoths, dinosaurs, ammonites, trilobites and of. .. unusually hot conditions The transition from isolated amino acids to DNA may then have happened in a hot-water system associated with active volcanoes, rather than in some primeval soup at the ocean surface There are two main kinds of hot-water systems on Earth today, ‘black smokers’ found in the deep oceans above mid-ocean ridges where magma meets sea water, and hot pools and fumaroles fed by rainwater... – such as the human arm, the wing of a bat, and the paddle of a whale These limbs may have different functions today, but they all 12 share the same bones and muscles inside, and we now know they evolved from the ancestral front limb of the first mammal The great leap forward Palaeontologists are aware that their field has transformed itself immeasurably since the 1960s, but public attention has focused . Ian S haw ANCIENT PHILOSOPHY Julia Annas ANCIENT WARFARE Harry Sidebottom ANGLICANISM Mark Chapman THE ANGLO-SAXON AGE John Blair ANIMAL RIGHTS David DeGrazia Antisemitism Steven Beller ARCHAEOLOGY. Beller ARCHAEOLOGY Paul Bahn ARCHITECTURE Andrew Ballantyne ARISTOTLE Jonathan Barnes ART HISTORY Dana Arnold ART THEORY Cynthia Freeland THE HISTORY OF ASTRONOMY Michael Hoskin ATHEISM Julian Baggini AUGUSTINE. Introductions available now: AFRICAN HISTORY John Parker and Richard Rathbone AMERICAN POLITICAL PARTIES AND ELECTIONS L. Sandy Maisel THE AMERICAN PRESIDENCY Charles O. Jones ANARCHISM Colin Ward ANCIENT