Their Brains Were Small and They Died

Remember geological ages? Maybe you have enjoyed interesting dioramas of life in the different ages at a museum. Scientists have differentiated many of them, but let’s start just eight back – with the Triassic – an age of dinosaurs and the very first mammals. Then came:

  • Jurassic: dinosaurs were IT and the earth was covered with giant ferns and other enormous plants, and atmospheric carbon dioxide was 1200 – 1500ppmv
  • Cretaceous: last of the dinosaurs, first of the flowering plants, and recognizable birds
  • Paleogene: a tropical age, but gradually cooling to an ice age, grasses, the first large mammals, and the highest concentration of CO2 ever 3800ppmv, falling to 650ppmv
  • Miocene: Ice ages, first modern mammals and birds, first apes, and carbon dioxide down to about 100ppmv
  • Pliocene: still Ice Age, appearance of Homo habilis
  • Pleistocene: Ice ages, stone age humans, CO2 at 100 to 300ppmv
  • Holocene: (the last 10,000 years) the ice recedes, human prehistory and history, carbon dioxide up to 385ppmv

Now obviously these ages shade from one to the next and there are no sharp dividing lines between them. But in general, what distinguishes one from the next is a particular climate, home to a particular set of plants and animals – plants and animals that do not thrive (or perhaps even survive) in different ages.

A natural ecology is too complex for us to understand, or even map completely. But it is perfectly clear that the climate, plants and animals interact in innumerable ways to produce a particular ecology. Make too many changes, and the whole system will shift to a new environment (geological age) which will be home to different life forms.

So what does it take to produce a new geological age? “According to members of the Stratigraphy Commission of the Geological Society of London:

  • Change the atmosphere’s composition, thus modifying plants
  • Change the distribution and diversity of species, thereby changing the future fossil record, and
  • Acidify the oceans, which will modify mineral deposits on the ocean floor.

Sound familiar?”

Yes, we seem to be bent on bringing about changes that will lead to a new geological age. Will we be able to thrive in it, or even survive?

Nobody knows.

As folk singer Faith Petric says, it may well be said of us as it was of the dinosaurs, “their brains were small, and they died”.

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