As science advances, it becomes possible to ask grand questions and work on overarching themes. This brings together multiple disciplines with the hope that we may get a comprehensive understanding of the issues facing us.
One of chemistry's greatest triumphs has been to be able to catalogue the entire set of elements out of which all matter is made. Physicists have been working on the “grand unification” of all fundamental forces of nature – gravity, electricity, magnetism, the structure of matter and relativity. Biology has been attempting to understand the genetic basis of all living matter and how all life is connected.
How are these various branches of science connected, how do they interact with one another, and thus how do we understand many of natural phenomena and events? This is even a greater challenge that brings together practitioners of various disciplines.
One such grand challenge of today is to understand how the climate in and around the world has been changing and how it will affect life on earth, and thus human civilizations. We have changed the environment around us, and need to undo the ill effects it has produced. This is one of today's grand challenges of survival.
It is in this context that an attempt is being made to understand how climate changes in the past had affected life on earth and the evolution of humans.
Go back in history. Our earth is over 4 billion years old, and has gone through a multitude of changes. As one of many celestial bodies, it has been feeling the effects of its neighbours, near and far; collision of comets and meteors, radiation from the sun, and radiation (radioactivity) from within its belly.
The grand and complex inorganic chemistry among the elements contained in the earth gave rise, over time, to organic chemistry – and by the time the earth became a teenager (3 billion years ago), life became possible on earth. We are thus the children of those grand, epoch-making events. Each of these events changed the environment and ecology within earth and around it. And life evolved thorough these vicissitudes.
Biologists who study the evolution of life on earth belong to two classes. One of them believes that evolution has been slow and steady, creeping its way from the archaic amoeba to animals and man.
The other class says no, it has been through sudden jumps and jerks, influenced by events that had great effects on the progression of evolution.
The first group calls the second ‘jerks' while the latter call the first “creeps”. The jerks ask: “how did so many life forms suddenly bloom on earth 500 million years ago at the Cambrian era?, or “how did the dinosaurs and thousands of other species disappear in one shot about 65 million years ago?
It is now possible, thanks to advances in a variety of scientific disciplines, to pose the grand challenge of “understanding climate's influence on human evolution”. Note that the question is limited to human life; this already restricts the period to just about 6-8 million years ago when the apes are believed to have evolved, and eventually gave birth to humans, about 2 million years ago.
Restricting the period simplifies matters a bit. If we further section it to periods of the human era – we can ask sharper questions. What gave rise to bipedalism (walking on two feet, hands free), why did we move from the Rift Valley of Africa to all over the globe? Why only through the West Asian route or the Indian route? How and why did we cross the Bering Straits?
The right questions
In order to understand an issue, you must ask the right questions.
One such is “what has been the influence of climate on human evolution?” It is this grand question that the US National Academies of Sciences, of Engineering, National Research Council and the Institute of Medicine have posed. They are now putting together a plan of action. The pre-publication version of the paper is available at www.nap.edu/catalog/12825.html.
Let me quote from their summary. “The hominin fossil record documents a history of critical evolutionary events that have ultimately shaped and defined what it means to be human, including the origins of bipedalism; the emergence of our genus Homo; the first use of stone tools; increases in brain size; and the emergence of Homo sapiens, tools, and culture.
“The geological record suggests that some of these evolutionary events were coincident with substantial changes in African and Eurasian climate, raising the intriguing possibility that key junctures in human evolution and behavioural development may have been affected or controlled by the environmental characteristics of the areas where hominis evolved.
“However, with both a sparse hominin fossil record and an incomplete understanding of past climates, the particular effect of the environment on hominin evolution remains speculative. This presents an opportunity for exciting and fundamental scientific research to improve our understanding of how climate may have helped to shape our species, and thereby to shed light on the evolutionary forces that made us distinctively human”.
To me, this is an exciting project for us in India to take part in, as part of an international effort. More on that in the next column two weeks from now.