The study of biology covers the width and breadth of life on Earth, and potentially beyond. The National Academies of Science defines life as “self-contained, self-sustaining, self-replicating, and evolving, operating according to laws of the physical world, as well as genetic programming.” We are enveloped in life on all scales here on Earth, from single molecules, bacteria and viruses to giant Redwood trees, diverse ecosystems and the biosphere as a whole, all of which both responds to and shapes the physical environment in which life is found. The processes involved in this surfeit of life forms are equally diverse, from simple to complex, and occurring in both the blink of an eye and over billions of years.
A brief glance out the window reveals an array of life forms, from squirrels to grass to other humans, but the various kinds of plants and animals that we regularly see can present a misleading view of the nature of life. In fact, the vast majority of life on our planet is microscopic. Of species within the animal kingdom, mammals, fish, birds, reptiles, and amphibians together represent only 3%. The other 97% of animals are invertebrates — animals without a backbone — and, furthermore, plants far outnumber animals. So although the world’s human population is a staggering 7 billion, we are dwarfed by much greater populations of microbes, insects and shrubs. In this context, how do we understand our own significance? And what role do we play in the earth’s ecosystem?
The tremendous variety of life on our planet may threaten to overwhelm our ability to understand it, but there is also a deeply unifying basis of life: all organisms are related by evolution. Evolution is the process by which diversity within and between species is generated through the inheritance and variability of genetic material. Deoxyribonucleic acid (DNA) contains all of the information that organisms need to grow, function, and multiply, and it is passed from one generation to the next. However, through mechanisms such as genetic mutation, minor variations between parents and offspring regularly occur. Most of these are neutral and some are harmful, but some are advantageous, and as genetic material passes from one generation to the next, the mechanism of natural selection identifies and propagates those traits that are most beneficial. Thus, over numerous generations, a group of organisms can accumulate enough genetic changes that they will no longer be able to interbreed with other members of their species. At this point a new species has evolved.
Evolutionary processes are responsible for the astounding diversity of life on Earth as well as the often-remarkable similarity of structures and characteristics across species. It has enabled life to be profoundly robust, adapting to continuing environmental changes throughout most of Earth’s history. However, the subject has also been the focus of a great deal of heated discussion, much of which is related to the relationship between science and religion. What does evolution imply about the origins and uniqueness of humans? Does it speak to the existence of God? How do Judeo-Christian traditions rectify the first two chapters of Genesis with modern science? How is the so-called human condition related to our evolution from non-human primate ancestors? Are human ethics grounded in evolutionary processes? These questions and others have occupied the minds of scientists, philosophers, theologians and the public at large from the moment Charles Darwin first published On the Origin of Species.
Advancements in the life sciences in recent decades have expanded both our understanding of the principles of life and our ability to apply biological solutions to societal problems. As with most advances, however, new realms of technology and applications also introduce never-before-considered ethical and religious considerations. For example, biological researchers must consider new ethical challenges as they explore the use of embryonic stem cells; the agriculture and food industries must examine the long-term effects of producing Genetically Modified Organisms (GMOs) for consumption; and society at large must contemplate the use of various reproductive technologies – from contraception to in-vitro fertilization. The medical fields alone supply a lifetime worth of religious and ethical questions around such issues as patient care, the use of animals in research, and even the determination of when an individual can be proclaimed dead.
The life sciences touch upon nearly everything under the sun, but they also are concerned with the most intimate of subjects – human life and existence – so it is no wonder that such rich and personal fodder produces lively and vigorous discussion both within and beyond the scientific community. Yet, despite its potential for divisiveness, biology also highlights humanity’s undeniable interconnectedness with all life and even the cosmos as a whole.
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