The environment is much more than air, rocks and water. The entire planet is occupied with living creatures large and small. Life is the most important part of the environment for humans who are animals among animals. Humans live or die depending on the stability and endurance of the biosphere. Humans derive meaning from other life forms and the smartest, kindest humans study the biosphere , bond with and protect other animals.
Bacteria are the oldest, smallest, most adaptable life forms on earth. They can be found everywhere from deep ocean trenches to the uppr atmosphere and beyond. Multicellular life depends on ancient bacteria that inhabited nucleated cells as mitochondria that supply energy to the cell. All humans contain mitochondria inherited from their mothers. Animal life depends on oxygen supplied by plants and single-cell phytoplankton floating in the upper levels of oceans.
An ecosystem is a community of living creatures that interact in complex ways. All ecosystems depend on environmental resources The sun supplies the energy. Photosynthesis converts atmospheric carbon into organic molecules. Animals feed on plants and on one another, moving life molecules and energy through the system.
Bios is life and a logos is knowledge. Biology. the study of life is now immense and complicated. Biologists work in diverse and specialized environments. In universities, biological disciplines are dispersed in different departments. Undergraduates take beginners courses in biology and cannot understand the whole when they study the parts. Students in universities may never study biology, so that “well-educated “students are often ignorant of biological concepts and have little or no insight into life processes. Since humans are living creatures, dependent on living creatures, you would think that biological knowledge should come first. What could be more important?
Ecologists who worry about human destruction of habitats try to teach other humans about their interdependence with plants and other animals. Non-biologists tend to exploit their home environments with little awareness of longer term consequences.
Botanists study plants and Zoologists study animals. You learn that plants are self-sufficient creatures who make their own food through photosynthesis using energy provided by the sun. Animals are dependent creatures who eat plants or eat other animals who eat plants. Humans are omnivores who eat both plants and animals. Both plants and animals reproduce sexually with female parts that make eggs and male parts that make sperm. Plants make seeds and animals make eggs or give birth to live babies. Plants do not have brains, and therefore exist without minds. Animals have brains and the degree of sentience depends on the complexity and sophistication of the brain. Worms with little brains are less sentient than humans with big brains. This is not to argue that worms are less successful creatures than humans since they may still be alive and well a 100 million years from now, and humans may disappear rather quickly.
The first living things on earth were bacteria in the sea. They were microscopic and had tough membranes for protection. Their descendants are still alive and well in all the oceans of planet earth. Some bacteria invented photosynthesis and gradually manufactured our oxygen rich atmosphere. Some cells eventually became larger eukaryocytes, with softer membranes who ate smaller cells with tough membranes. Some bacteria came to live inside the larger cells and are now present in every animal cell as mitochondria. Eukaryocytes joined together in clumps and eventually learned to differentiate into specialized tissues, becoming plants and animals. Cell clusters have differentiated into tissues that most modern animals share – skin, nervous system, digestive system, immune system, respiratory system, circulatory system and reproductive system.
Life is based on carbon atoms that can combine with up to 4 other atoms forming carbon bonds. Biochemistry is the study of the complex interactions of carbon molecules that create life. A rapidly expanding field of molecular biology reveals the chemical organization and activity within cells, linking the genetic code with the biosynthetic pathways that are required for cell growth, maintenance, repair and reproduction. Organic chemistry is also the basis for industrial manufacture of diverse materials that have become ubiquitous on planet earth.