The 10 biological imperatives of life, including Homo sapiens
1/ Oxygen (air). The element oxygen is imperative for almost all life on Earth. Our atmosphere is 21% oxygen with the rest made up almost entirely of nitrogen along with other gases at pretty much trace levels. Oxygen is the element in air that allows animals, including humans, to conduct the chemistry of life. The 21% is critical because below 17% not enough oxygen is present to allow for comfortable breathing and oxygen levels above 25% creates highly flammable environmental conditions. Without exposure to air that contains the proper oxygen level, animals die relatively quickly. Thus air (oxygen) is the most immediately critical imperative for human life.
2/ Water. Water is a molecule composed of one atom of hydrogen and two atoms of oxygen. It has a liquid, vapor, and solid form, and as a liquid it is the ultimate solvent and is present and critical to the chemistry and conduct of the life of plants and animals. Life as we know it cannot exist without the presence of water. In one way or another all animals ingest and excrete water and without this compound, life ends. A human body is 60% water and needs about 2.5 quarts every day taken in as liquids and as content in food. Without water intake, the human body will die in three to five days when deprived of water. Thus availability of water is the second most critical imperative for human life.
3/ Food. Human intake of food is highly variable, dependent on location, culture, economics, personal preference, and availability. Being biologically omnivorous, humans eat both plants and animals and can survive on many various diets, some healthy and some not healthy. Without available food suitable to the species (including in some instances a symbiotic association with plants), animals die. In a situation with total absence of food, most humans will starve to death within three to four weeks. The critical element in food is carbon. Life on Earth is based on carbon because it easily bonds with most other elements, especially oxygen, hydrogen, and nitrogen, and forms molecules of fats, proteins, hormones, DNA, sugars, is present in all body tissues, and is the critical player in the physiology of life. Actually carbon is food and humans consume carbon in every meal. Starvation is a highly variable process and depends greatly upon the condition and circumstance of the individual. However, life, including human life, requires frequent intake of nutrients suitable for fueling the physiology of the physical body, thus food is the third most critical imperative for human life.
4/ Elimination. Elimination of urine and solid waste is usually overlooked when imperatives/requirements for life are discussed. After all, it does happen pretty much automatically and it is a biological corollary of ingestion and processing of water and nutrients by both plants and animals. With animals urine containing water and metabolic waste must be eliminated often, at least several times a day, and solid waste must be eliminated regularly every day or at least every few days and if elimination does not happen, life cannot continue for very long. Elimination is a critical imperative for life and ranks on the same level as water and food.
5/ Sleep. Sleep is a complex essential behavior to animals with brains and it varies greatly in the animal kingdom. It is keyed to the circadian timer of the species and is also evolved to adapt to the environmental requirements of different species. For example some species sleep at night and some sleep during the day, some sleep for short periods, only 3 to 5 hours and some for long periods, 18 to 20 hours. Some species sleep with only parts of their brain at one time, for example dolphins have unihemispheric sleep, only one side of their brain sleeps at any one time while the side that is awake maintains movement and environmental awareness. Although the requirements and conduct of sleep may vary, sleep is essential to healthy brain activity and animal with brains require some form of sleep. Without sleep, perhaps a week or two, perhaps a few months at most, humans die. Thus for animals with brains sleep is imperative for life.
6/ Shelter. The need for shelter among animals is also greatly variable, as is the definition of shelter. Shelter is typically a place where it is safe to sleep, where the animal is protected from whatever there is in the environment that threatens life such as excessive, cold, heat, sun, water, wind, and predators. Seeking shelter may be an instinctive reaction or a thoughtful selection of a protected area, and usually both. It may be a particular place found or constructed such as a cave, a burrow, a nest, a cover of sand, a tree, a coral reef, a house, or an apartment in a city (humans, cockroaches, ants, and mice); or it may be just the shelter, sustenance, and safety provided by conspecifics such a huddle of penguins, a herd of buffalo, a school of fish, a clowder of cats, a pack of wolves, a colony of rats, a flock of birds, or a tower of giraffes. In all cases, shelter is recognition of, or manufacture of, an environmental niche that affords some degree of protection from the dangers inherent in the ecosystem that the species has evolved to inhabit. Some recognition or enhancement of an environment that provides protection to an animal species is imperative to the life of individuals of that species. Without the “shelter” that is required by the species, an individual has little chance of survival. The time frame of the life of an individual that cannot find safety and shelter is variable, but seldom long.
7/ Conspecifics. Conspecifics are members of the same species. A species is more than a group of individual plants or animals that through their genetic sympatry have to the ability to reproduce with each other. In an ecological framework they are a family, flock, herd, gaggle, group, school, tribe, culture; a small, middling, or vast aggregation of individuals that form a gene pool. A gene pool is a body that is more than a random collection of individuals; it is a genetic entity that is in competition with other gene pools, and members of it’s own gene pool as well, for space and sustenance. This mix of competition and dependence drives its capability to evolve and adapt to changing environments. Every gene pool (species) is always dependent on other gene pools for its survival and evolution. All of humanity is conspecific; we are all part of the greater homo sapiens gene pool, and like all other species, we are dependent on our conspecifics for our individual and group survival. We are also dependent on the other species of plants and animals that occupy this Earth for our own survival. From birth to death, we receive life and give life to our conspecifics. We also, like many other species, often take life from our conspecifics in a competition for living space and sustenance, but to a greater extent, interaction with conspecifics, whether just for exchange of genes, or for cooperation in large or small groups, is usually imperative for individual survival and always necessary for species survival.
8/ Reproduction. Reproduction, particularly in the context of childbirth and family units, is imperative to survival of infants, children, family, tribe and immediate societal structures. Almost entirely, reproduction in animals and most plants is dependent on division of the individual genetic complement and joining of half the genetic code of each parent to create an individual with a unique genetic code. Male and female sexuality and most all other physical traits as well, is determined by the recombination of genetic information (DNA) from each parent in each individual offspring of those parents. Reproduction drives the life and behavior of all organisms and Homo sapiens is not an exception. Without successful individual reproduction, an individual human being can survive and live a natural life span, but the genes or that individual, including beneficial and harmful mutations and combinations that might have occurred and that that individual carries, will not survive and will not contribute to future generations.
Reproduction is also dependent on sexual behavior, and sexual behavior varies greatly in presence, season, and intensity in diverse animal species. In humans, our sex drive, the sexual awareness and biological need that drives reproduction, is enormous and always present. Sexuality is somehow “under the covers” of pretty much every human endeavor. The demeanor and conduct of Interaction between individuals is greatly dependent upon the gender of the individuals. Gender affects the interactive behavior of individuals even when sexuality is apparently ignored. Sexuality is always present in one way or another in human comportment from childhood to old age, and dominates our behavior, our physical structure, our cultures, our customs, the way we dress and present our appearance, and in all our interactions with other individuals. Although human gender is determined by our genes, our evolutionary past and our cultures have also inserted a greater lability into our sexual orientation and behavior than is found in most mammals. This variability in social sexual behavior may be of positive or negative survival value to individuals depending on cultural circumstances. But apparently, because of the lability of sexual orientation and behavior in all the various populations of the human species this trait was/is in some way advantageous to the survival of the human species.
Like the oceans that cover most of our Earth, our sex drive can rage with the intensity of a hurricane and dominate and control all thoughts, behaviors, and actions; or it can rest uneasily under a calm social surface that hides the ceaseless swells and currents of sexual thoughts. Although behavior driven by sexual desires often break the surface of oceans of cultural correctness and proper asexual behavior in vague expressions, jokes, innuendoes, and even subtle looks and touches. With most other mammals sexuality is restricted by a biological imperative of season and sexual heat; whereas with humans, it is our cultures, that imperfectly control our sexuality and by definition, our reproduction. Thus the sexuality of reproduction is a biological imperative, not for survival of the individual human, but as it has evolved in a multitude of ways to provide for the survival of all species now in existence, it is also a behavioral imperative for survival of the human species,
9/ Birth. Obviously the birth of a human being or other animal is the first individual essential for survival. It is a biological process that every living human has experienced. Most of us traveled through a birth canal, but now many are delivered by caesarean section, surgically opening the womb through the abdomen to remove the baby. Up to the mid 19th century this was a very small part of the human birth experience done only under extreme and life-threatening conditions where the mother seldom (never) survived. When antibiotics and sterile surgical techniques were developed, survival of the mother became common and it is now an important part of human survival during the critical birthing processes of humanity. This is a prime example of how modern medical technological development has altered the fundamental essentials of human life. Birth, the beginning of a new individual, is the biological culmination of the reproductive process, a process that is essential to survival of the human species, and all other multicellular species as well.
10/ Death. One may not think that death is imperative to survival of the individual, and obviously it is not. Ever since the development of abstract thinking, humans have known death to be the end of biological life, but many (most) have and still do, consider death as an ending that is not necessarily the final ending that God(s) intend for human beings; and through an anticipated supernatural intervention, an ending that might not occur, or that could, would, and might even be rescinded. But biological death for individuals of basically every multicellular species is imperative in the same sense that reproduction is required, not for survival of the individual, but for survival of the species.
Life spans are variable between species and within species. Some species such as the mayfly have a life span measured in days, while others such as the Galapagos tortoise have life spans of up to about 200 years, and some greater than that. What would happen if aging and death were not part of the genetic inheritance of individuals that compose a species? And why is the life span and assured eventual death of an individual important in the evolution of all life?
The life span of an individual organism is “written” into the genetic code that is common to the species, and this is so because without a biological balance between the life span of the individual and the reproductive rate of the species, as determined by the evolution of the species within the ecology of an ecosystem–the species will become extinct. Life spans of the individuals that compose a species are variable within a broad or narrow time range, and like other biological characteristics unique to that species, are subject to changes demanded by evolutionary biological change. Survival of a species within a natural ecosystem depends on the ability of the species to evolve. Overproduction or underproduction of individuals (reproduction without death, or life without reproduction) would either drive the species to extinction or drive the ecology of the ecosystem into a new balance, which would effect change in all species that are part of that ecosystem.
Thus death of the individual is a biological imperative for the life and vitality of the species. Individual death is biologically “prearranged” to meet the survival needs of the species within the ecosystem in which it lives. Humanity is at the very beginning of understanding and directing its own genetic codes, which could possibly extend individual life to unknown limits. However, if we succeed in developing this technology, it could have great unforeseen effects on our existence as a biological species and on the ecology on which we depend for the life of our species. A world without timely human death for all or even for just a few, would have huge social, cultural, economic, ecological, and biological ramifications that, if our species survives and adapts to great individual life spans, would greatly change who we are and what we are. As long as Homo sapiens is dependent for its existence on a healthy natural ecology on this planet, our allotted life spans and our populations must be in keeping with the biological imperatives of life on Earth.
Homo sapiens, the gene pool that is currently humanity, evolved in a tropical/temperate terrestrial environment. We are ecologically adapted to that basic ecosystem and we can, and in small measure still do, survive quite well in small extended family and tribal cultures in natural environments without much contact and dependence on the mores and technology inherent in modern human cultures. However, technology has allowed us to also survive in environments totally inhospitable to human life, such as on the surface of oceans and lakes, at the bottom of deep and shallow seas, in caves and mines deep under the earth, in the extremes of Artic and Antarctic winters, and for years about 250 miles above the earth in the cold emptiness of open space, and even for a short visit to the surface of the moon. But we are still prisoners of the biological imperatives created when biological evolution formed our species.
When we venture out of the ecosystems that gave us birth, we can only survive if we package our biological, physical, ecological, and cultural imperatives and take them with us. And our survival is measure by the length of time, minutes, hours, days, months, years, that we can maintain these biological imperatives in hostile environments. Human colonization of unknown and inhospitable environments is difficult and in order to survive in the most alien of environments, where the biological essentials are not naturally available, a lifeline of supply and care must be established and maintained from the mother civilization to the colony. The more alien the new environment the greater the need for close contact with the civilization that supplies the imperatives of human life.
Over many thousands of years, our species, Homo sapiens, has made the Earth into what it is today, a plethora of interrelated ecosystems that are in danger of collapse from the weight of human use. Despite our wishful human imaginations, there will be no glorious supernatural ending to our world. The lion will not lay down with the lamb. The Earth is what it is, it is what we have made it to be, and survival of our species, the promise of what we can be, and the critical support for human life provided by the ecology and ecosystems of our Earth depends on what we humans do over the next few years, and on into the next 100 years. We can be the first of a great new human culture that supports the Earth as it supports us, or the last of a great, but fatally flawed, human exploration into a civilization based on science and technology, but ruled by economics and supernatural belief that ignores the necessity for ecological stability of life on our unique planet. Unless we learn self control from our flirtation with global civilization on this planet we will not survive to find another. Emigration and establishment of a self sustaining presence on another planet will not be as “simple” as an ocean voyage to a “new” world.