About 2 million years ago early hominids evolved into species which show much more human characteristics– mostly associated with a larger brain. One of these– Homo Erectus– came out of their homeland Africa and colonized far away places in Asia. But even more intelligent human species evolved later, again from Africa. Some of them went to Middle East and Europe some 3 hundred thousand years ago. We know about them from many Neanderthal (as they are called) fossils and camps. But we Sapiens came even later, and replaced the Neanderthals and Erectuses everywhere. The fossil story is confirmed by the latest DNA studies which beautifully traces our Sapiens ancestors’ migrations throughout the world, and possible cohabitation they had with the Neanderthals till some 30 thousand years ago. But Sapiens then steadily progressed towards creating civilization that allowed them eventually to conquer the world, and their own biology to some extent.

There is not a shred of doubt anymore about the stark reality of the Green House Effect. The whole world, and specially we in Bangladesh, are extremely worried. Most of us know about the things that are happening and will happen with increasingly more serious consequences because of this. But few of us know about the researches revealing the facts. The scientists have very carefully searched for long within the depths of accumulated ice from thousands of years, within the turbulence of the ocean waves, up in the atmosphere and beyond it through the remote sensing from the space, to discover and confirm how we are accelerating towards such a bleak scenario. The story is exciting as it is of serious concern.

During the last 550 million years of the history of life there have been a number of mass extinctions which are very significant. Though these caused large scale extinctions of species and families of life, these also created opportunities for radiations of new species with new possibilities and diversity, out of the few which survived the events. We will follow these events as milestones in our journey through relatively recent history of life in which one group of animals dominated in one particular phase, later giving way to another. The way the changes in the earth itself− the reorganization of continents, severe climate changes, and accidents such as huge meteorite strikes− have caused sharp turns in this history, is very fascinating indeed.

During the long 150 million years of Jurassic-Cretaceous period Dinosaurs ruled most of the niches in the earth. Then everything changed because of the mass extinction 65 million years ago− the last of the mass extinctions which we usually refer to as KT extinction. Thanks to the precise measurements made possible by modern physics we now know that a huge meteorite strike at the Gulf of Mexico created that catastrophe. This killed all dinosaurs and many other species but spared some of our small mammal ancestors including some early primates. It is this chancy survival that enabled those wonderful steps towards intelligence which has reached to such achievements in human. But alas we ourselves are now slowly causing another mass extinction− the first one not created by nature.

Topic: How Do We Think

It is the intelligence and higher thoughts which have given the human beings absolute dominance over other forms of life. But what comprises that intelligence, and what is the mechanism of these higher thoughts? We know that our brain is the site of our thoughts and consciousness. Memory, language, self-consciousness, mood, emotion – all play a part in this. Can we explain all these in terms of the works of neurons in our brain? Many of the answers are now within the grasp of modern science. Neurology has seen wonderful progress in understanding the process of thought. Very recent discoveries of medical imaging and the computer science of artificial intelligence have been great helps in this.

In understanding the process of thinking the challenge that always came to the forefront is to correlate this directly to the physiology of the brain. This has been attempted through research by three different means: 1) Studying during operation the effects of the damaged brain-parts in patients, 2) studying animals, 3) Modern brain imaging techniques. Also the long research background of the behavioural psychology helps. The inputs into the thinking process come through the windows of the sense organs. That is why it is important to know how each of these create responses in the brain. But the brain does not depend only on these in its creation of the mental picture of the world around. Rather it creates parts of the picture on its own. How it does this is an amazing story, particularly the creation and storage of memory that contributes to that picture. The story is now being revealed thanks to the latest advances in science.

Two sources supply the raw materials for our thoughts— sense  perceptions and memories. The process through which short term memories are converted into long term memories to be stored and recalled for many years, is subject of intensive research. Most of the scientists agree now that these memories are stored in our brain in the form of patterns of the strength of synapses- the connecting devices between the neuron cells. Something learnt or experienced creates a nerve signal in the brain which is temporary, but this leaves a characteristic permanent pattern of the varying strengths of the synapses, representing the memory of the experience. At a cue much later, a fresh current follows this pattern recreating the original signal pattern and thus recalling the memory. A similar recall is created during dreams or day-dreams, but with less control of the higher levels in the brain. The process of learning is also closely   related to that of memory.

What is intelligence? According to most modern theories it is the ability to guess right. What we need for this are imagination, judgment, and logical deduction. According to many scientists the process works through some neuron pattern of perception in one area of brain creating many slightly  different clones in adjacent areas, and a competition among these. Though the evolution of intelligence took place in many species, it has achieved a unique high ground in human brain. Imagination creates random neuron patterns from which the most elegant one is filtered out in the process of creativity. There is a central role of language in all these. The area in ape-brain which corresponds to the language-area of the human brain deals with complex hand movements. This inspires the theory that language has been evolved from abilities for such movements and tool-making. Indeed there is a resemblance between the hierarchy of tool-making process and that of grammar. Actually there seems to be a universal grammar inherent in human brain, thus evolved, modelling all grammars of all languages. The scientists are now revealing the interesting processes through which language works within our imagination, creativity, and at the very core of silent thoughts.

Lecture-5: 12 April 2009

The part of the thinking process which is found to be most difficult to explain is consciousness. It is through the consciousness that we ‘know’ we are conscious, can exercise free will, and can let others know about this. It has three components: self-consciousness, access to information, and sentinence. It is now realized that a continuous self-consciousness is basically a unique human quality. The access to information is related to the attention on a certain thing, which again works through a synchrony of neuron firings at various parts of the brain. But the sentinence, meaning very personal sensations, is still shrouded in mystery; for example we still do not have a theory which can predict what the fragrance of rose means to a certain individual. Very recently, experiments have shown that our brain can take a decision seconds before we become conscious of it. This raises the question whose consciousness or whose free will we are talking about. Emotion is intricately connected with consciousness, and is equally difficult to explain. But the process through which emotion and mood work in the brain to create bodily reactions are now well understood, and can be controlled to some extent. In general we have been able to explain much of our thinking process, but some old problems still remain as a challenge.

Topic: Biodiversity and Our Future

Our life, and the fate of the human species in future will very much depend on how much of the present biodiversity survives. The question is critical now because a serious threat has been created on the biodiversity, a threat totally new in the 4 billion years history of life on earth. This is because one species the human– is its cause. Any effective measure of the prevention will need detailed knowledge of the complex interactions among the many species within an ecosystem. The research is not an easy one, we do not even know the exact size of the biodiversity. The total number of species so far identified by the   scientists and nature explorers is 1.5 Million– most of these insects. But various mathematical modeling indicate it to be between 5 million and 100 million. While a large-scale extinction is going to be disastrous for our future, even the loss of one or two familiar species is a sad news for the scientists and nature lovers for various reasons. Our fate is inextricably bound with biodiversity from the bush near the household to the tropical rainforests and coral reefs– the hotspots of biodiversity.

Lecture 2: 06 July 2009

Our future is dependent on biodiversity, but much of our biodiversity is in danger now because of our own doings. We must closely monitor it and try to arrest the process of extinction of species. Latest and most sensitive scientific methods are being applied for such monitoring. For example, the abundance, health and mutual interactions of the plant species in a forest can be revealed through very fine analysis of gas exchanges. Gases involved in physiological processes such as photosynthesis, respiration, transpiration etc. can tell a lot for the overall composition at the forest canopy as well as for plants within a closed container in a lab. As for the wild animals– birds, fishes, mammals etc– modern telemetry embed Global Position System (GPS) and very sensitive miniaturised instruments in their bodies for continuously measuring heartbeat, blood pressure, oxygen intake etc. and transmitting these as radio waves, or sonic waves in the case of marine animals. It is also important to measure regularly the population of species in danger. Modern mathematical models such as within the metapopulation theory provide great help in this, as well as in planning for the restoration of a declining population. The recent Tiger Census in Sundarban, Bangladesh is a case in point. The census based on casts of the tiger foot prints has used very modern methods involving computer softwares, GPS and GIS (Geographical Information System). Our latest science should be fully deployed for undoing the harms we have already done to our biodiversity.

If we intend to protect biodiversity, we have to understand better the mechanism of its ups and downs. In every ecosystem, a good number of species live within close interactions, taking advantage of the specific ecological conditions available. Some species may have special roles to play within that community. For example, there are ‘Key Stone species’ which exert far greater influence on the biodiversity than what their numbers   warrant. A local example is the tiger in Sundarban. Of course the species are in competition with each other within the community. But that does not mean that only the winners prevail. Various needs for optimizations force all species to maintain a golden mean that allows a co-existence of many species. Similarly there are many subtle cooperations between species in a community, which need to be better understood. Ultimately the diversity depends on the primary producers in a ecosystem– usually the plants or phytoplanktons. They form the base of the food pyramid. Current research has shown how dependent the stability of this pyramid is on the biodiversity at all levels.

Lecture 4: 24 August 2009

Changes and equilibrium in the community of species in an ecosystem determine the biodiversity. The recent theories on these, derived from finer observations and mathematical modelings, propose somewhat unconventional theories. We realize now that the equilibrium is not a simple one as we used to think, rather, it is a dynamic and a chaotic one. Therefore, it has become all the more   necessary to study carefully while we decide our action plans for saving biodiversity. One of the most important things to save for this, is our rainforest. Much of the biodiversity of the world are  concentrated here, and Bangladesh has some part of it, though not the most dense part. The biodiversity of rainforest is immense− demonstrated by the wonderful varieties of roots, buttresses, bole       climbers, epiphytes, and canopies of its trees; and the insects, birds, primates and other animals that abound within them. But now these forests are approaching a very fragmented existence indeed, threatening the last resort of our rich biodiversity. One of our biggest battle in the struggle for biodiversity will have to be fought here.