2.0.5 How Life Diversified: Biology - Overview

Version 1.2 March 2012                                               (Previous Version)

Science understands how today’s complex life developed from early single cells.

Some people are so impressed with the complexity of life that they can't understand how it could happen with random mutations.  But the selection process is NOT random.

Some organs, such as eyes, and other biological systems, are so complex that it once was difficult to see how these could have developed accidentally.  Some people call it irreducible complexity.  But it's not irreducible: it can be reduced to a sequence of stages.

The detailed pages I Chapter 2.5 go through the stages of the diversification of life.

We can see in daily life random differences between offspring, in our children and animals.  We can see changes in bacteria in a few hours.  But offspring still inherit most of their parents’ traits.  Some traits are more useful in different environments, enabling the offspring to survive better, so they have more offspring of their own, passing on their own traits.  Over many generations the descendents can end up quite different from their ancestors.  The process of weeding out the less fit progeny is not random: it creates more complex designs more suited to the environment.

Asexual reproduction occurs in single cells when one cell splits into two, in some plants or simple animals by budding, and some fungi produce asexual spores genetically the same as the parent.

Sexual reproduction began with simple cells fusing and mixing their DNA molecules.  Many (single celled) eukaryotes reproduce sexually, as do multicellular plants, animals, and fungi.  Sexual reproduction is more complex but continued because it leads to more successful variation in the offspring, and reduces mistakes in the reproductive process.  Species with the strongest drives to reproduce became more common, and many of us now naturally feel strong sexual desires.

The earliest single cells split into plant cells that grow through photosynthesis and animal cells, which survive by feeding on other animal or plant cells.  Some single cells developed ‘sticky’ surfaces and evolved into multicellular organisms. Some cells switched on different genes, and grew into internal organs, muscles, cartilage and bone, and light sensitive parts evolved into eyes.  Nervous systems began as simple networks in which appropriate reactions to pain and pleasure improved survival rates.  Animal species especially built up more complex growth patterns, evolving into worms, insects, fish, amphibians, lizards, dinosaurs, birds and mammals.

Though species compete for food and for mates, many survived better when they also cooperated in group safety, locating food, water and shelter, and raising young.  We see this in social insects (bees and ants), many birds (some mate for life), and mammals (hunting packs and herd animals).

We work through the next level of detail on each of the above issues (more).  After considering this evidence, we’ve looked for a way to state our conclusions briefly, and we come to the following summary.

Is this the best way to state our conclusions in this area?  Click on feedback, or add a comment below, if you can improve the substance or the phrasing.

  more                                                              Statement 11

Science provides natural explanations for suffering, the so called problem of evil, as well as sexual drives and our instinctive need for cooperation and connection, and pleasure seeking behaviour.