why is evolution the "biological theme that ties together all the others"?

Answer 1

Well, to understand how things work you need to understand the differences. To understand the differences you also need to understand the similarities. These ties of similarity are there because of inherited traits, because certain genes were passed from offspring to offspring over time.

Because of this, mammals have certain things in common that they do not have in common with reptiles. However, mammals have more in common with reptiles than amphibians. We try to understand how cells function and how organisms develop and operate. For example, we test drugs on rats because they are mammals like us. These tests would not be as good if we used frogs or salamanders because these are less likely to act the same way.

Sometimes these relationships can be rather surprising. For example, all green plants have chloroplasts in their cells that produce chorophyll. The strange part is where these chloroplasts came from. At one time these choloroplasts were independent cyanobacteria. This is why chloroplasts stil retain their own DNA. Similarly, our cells contain mitochondria which were also once independent bacteria. Mitochondria too retain their own DNA.

Biology has changed over time. There are now specialties in cellular DNA and specialties in organic chemistry. Evolution is not something that effects biological study on a daily basis but sometimes it shows relationships and causes that are important. Evolution is not something that biologists have to be concerned about everyday but it is also a piece of the whole puzzle and not something that can just be ignored. I suppose the best way of thinking about it is like geology. The tectonic movement of Plates is very, very slow. Yet this movement formed all of the major mountain chains. You don't really have to deal with tectonics on a daily basis but it would be impossible to understand how mountains formed without it.

Answer 2

Evolution is relevant to the study of all organisms and to (almost) all there herritable characteristics, from the most microscopic level to social behaviour. So it touches most if not all other biological disciplines.

Answer 3

This is similar to an earlier question about the statement 'nothing in biology makes sense except in light of evolution', so here is a copy and paste of my own answer to that question.

There is an incredible diversity of living organisms on this planet. From microscopic virii that require other cells in order to reproduce to gigantic blue whales that cruise the depths of the oceans. Some are incredibly specialized: the fungus Laboulbenia grows exclusively on the rear portion of the elytra of one species of beetle, Aphenops cronei, which is only found in a handful of limestone caves in southern France. Other organisms are incredibly adaptable and can survive nearly anywhere. One species has even managed to use bits of its environment to modify its surroundings such that it can even survive temporarily well outside the Earth's atmosphere, and has even reached the surface of our lunar satellite.

At the same time, there is a continuity of general morphology. As different as the organisms of the Earth are, they also share a number of similarities. The basis of heredity in all Earth organisms is a few similar strands of nucleic acid. There is not one six-limbed vertebrate, even though there are other groups of organisms with multiple limbs. All of the vast variety of insects share a basic body plan of three body parts, six legs, and four wings. Even their mouthparts are amazingly similar, despite the wide array of different structures they have been modified into.

The theory of evolution, that simple idea that natural selection of variation within a population leads to changes in that population over time provides an explanation for both this extraordinary diversity, as well as this remarkable unity of morphologies.

Evidence supporting the theory comes not just from genetic and morphological comparison between the vast array of living species, but also comparison of fossil forms. The diversity, array and morphology of all of the fossils known have completely supported the theory of evolution.

In addition, the chronological ages determined for the fossils also fit into the pattern that would be predicted by the modern diversity of living organisms. The biogeographic distribution also fits this pattern, explaining things like why there are porcupines in Canada but not Russia, and why kangaroos are only found only in Australia. These pieces of evidence could be predicted by the theory of evolution and the evidence from geology of the ages and movement of the continents, and the actual facts again support the theory of evolution.

Other observed phenomena, such as drug resistance in bacteria, or pesticide resistance in mosquitoes can also be predicted by the theory of evolution. Indeed, we see these things happening, and evolution explains why.

No other theory in the entire field of biology has both the predictive and explanatory powers that the theory of evolution holds. Without the theory of evolution, the best explanation anyone could give about almost any observed behaviour, adaptation or morphological variation in the biological world would be "ummm... I dunno... that's just the way it is."

No other theory has as much physical evidence supporting it either, including well known principles as the theory of gravity, or the theory of heliocentrism.

The only opposition to the theory of evolution comes from a few camps who are upset that the particulars of how it reveals that life came about and adapted to the conditions of the Earth disagree with the creation myths set forth in their holy scripts, and a handful of people who seem to be mortified with the idea that we might be related to chimpanzees (as if being formed from dirt was somehow superior).

Answer 4

It is the explanation for the similarities and differences among organisms, including the adaptations they have to their environments. Without it, biology is simply description, not explanation.

Answer 5

because all the other bilogical themes: form and function, predation, competition, etc.. are subject (and due to) evolution.

Answer 6

Because it is backed by hard core evidence and not religious bulls**t.

Answer 7

bcuz it can provide clear, tangible evidence. not hearsay