Reasons Why Evolution is True Part X:
Convergent Evolution

When you design many objects that perform similar tasks, the logical strategy is to reuse the same design, perhaps with small modifications, for each object. There would be little point in coming up with a new design every time, right!? In nature, however, there are many species that do similar things but have arrived at their method through different designs. This is known as convergent evolution.

Intelligent design, and decent by modification, predict different patterns of similarities and differences between species. Evolutionary theory, which places all living things on a tree of relatedness, leads us to expect that species that are more closely related to each other should tend to be more similar. This is because they have both evolved from a recent ancestor. This ancestor has been ‘modified’ in various ways by natural selection to produce the two (or more) daughter species, but with a shared starting point for these modifications, we expect a fairly similar outcome. Traits that are shared between species due to shared ancestry are known as homologies. Homology has been the basis for determining relatedness between species (phylogeny) for hundreds of years. However, as early taxonomists noted, there are some occasions when species share traits despite the lack of a recent common ancestor. Often these species have reached a similar solution to a shared problem, despite being only very distantly related. This is known as convergence, and the more we look for it in nature, the more we find.

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Reasons Why Evolution is True Part IX:
DIY Evolution

Although some people may try to refute the theory of evolution, nobody can deny that natural selection occurs. We can demonstrate this quite easily within a single human lifetime, and humans have been inadvertently using natural selection to our own advantage for over 10,000 years. The processes I’m discussing, of course, are artificial selection and domestication.

When Darwin first began to think about evolution, one area of greatest interest to him was domesticated species, in particular the pigeon. The pigeon exists in around 300 of varieties, which have been selected for by pigeon fanciers for at least 5,000 years. The similarities between domestic pigeons and their wild counterparts are clear, however it seems that humans have, over many pigeon generations, been able to shape many aspects of their appearance including plumage colour and shape, body size, and beak shape. Other domesticated species such as dogs, cattle and even crop plants, have undergone significant changes in their appearance and internal anatomy since humans first began breeding them.

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Reasons Why Evolution is True Part VIII:
PreCambrian Rabbits

The fossil record is one of the most obvious pieces of evidence for evolution. Fossils have been known since human history began, and Aristotle first noted the similarity between fossils and living animals, leading him to conclude that fossils represented deceased creatures, a view supported by Leonardo da Vinci. By the 19th century, people were increasingly beginning to appreciate that some fossils represented extinct animals, and that their positioning in the rocks appeared to represent that passage of time. Now there is also ample evidence from molecular genetics and radiometric dating that the fossil record does represent the evolutionary history of life on Earth. Despite this, creationists still continue to argue otherwise. Some have suggested that the fossil record represents animals killed during one or more biblical floods, however this is incongruent with the evidence available.

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Reasons Why Evolution Is True Part VII:

Few species go through life without interacting with an other, but some interactions are more intimate than others. Pollination is an example of an interaction that, in some species, has become very intimate indeed! Most dedicated pollinators show adaptations to this, such as pollen baskets in bees, but these are often generic adaptations that enable the individual to visit many different species of plant. Equally, plants have adaptations to attract a variety of different insects. Different pollinators (bees, birds, moths) have different visual systems, and thus different flower colouration can be used to attract pollinators of different species. The timing of flower and pollinator emergence is also carefully timed in order to ensure maximum cross-over between the two. Pollinators generally gain food from the relationship, whilst plants achieve dispersal of their genes without having to physically move themselves.

Some plant-pollinator interactions are more intimate, more specific. This can lead to more extreme adaptations, as the two species become increasingly specialised for interacting with one another. Possibly the most extreme plant-pollinator relationship exists between the fig and the fig wasp. Young fig wasps emerge as larvae inside a tiny fig. The larvae feed on the fruit of the fig until they are ready to mature into adults, which again occurs within their fig prison. As adults, the wasps mate, collecting pollen from their birth fig before they leave. The male fig wasps then dig their way out of the fruit, creating a path for the females to emerge from. The male fig wasps are not well suited to life outside the fig, however, and often die shortly after making their escape. The females fly off and find a new fig plant where they can lay their eggs. Squeezing through the tiny entrance hole, known as the ostiole, the female enters a new fig and deposits her eggs inside the fruit, simultaneously depositing pollen on the fig’s reproductive parts.

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Reasons Why Evolution is True Part VI:

Although it makes sense to stick with a good idea when you’ve found it, you wouldn’t stubbornly stick to the same design even when it wasn’t quite working properly, would you? And yet this is just the pattern that appears in nature. Life on Earth shares a remarkable list of features, from protein-handedness and membrane structure to the DNA code. While some of these features, such as protein-handedness (which way around proteins are formed), are inconsequential, others are not. The genetic code is almost completely universal across all life. This is the reason GM can work, because a gene coded for in the genome of one species can be read by the translation machinery in another species’ cells. This does not necessarily have to be true, however, as the code is arbitrary and there are many possible configurations which would work equally well. Furthermore, the code is actually detrimental for some species living in extreme environments, since certain codes are more volatile than others. Despite this, the code is shared by all.

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Reasons Why Evolution is True

Across the next 10 articles, I present a few of the quirky examples of evolution that we can readily observe in nature. It is by no means an exhaustive list, but merely a set of stories which I feel illustrate well the power of evolution to create complexity, and how we can see evidence for natural selection by looking carefully at the idiosyncrasies it has produced.

The examples I provided in this series can be broadly categorised into a few themes; coevolution (Fig Wasps and Hawk Moths), evolutionary constraints on adaptation (Pandas, The Human Eye), convergent evolution (Birds and Bats), adaptive radiation (Galapagos Finches, Ring Species) and homology (DNA and the Pentadactyl Limb). And within each of these categories, there are numerous other stories I could have told to illustrate my point. But the point I am trying to illustrate is that evolution is a real phenomenon. Charles Darwin’s theory of evolution by natural selection is one which explains the natural world around us in both a satisfying and verifiable way.

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Reasons Why Evolution is True Part V:
The Quirky Human Eye

The mammalian eye, a refractive cornea non-compound eye, to be precise, is a wonderful example of the bizarre quirks of evolution that we see in nature. These are only really bizarre, of course, from the view-point of intelligent design.

Our visual system is made up of many tiny light receptors on our retina known as rods and cones. Each receptor picks up a small portion of light and relays the message to our brain via nerve connections in the optic nerve. Information from thousands of light receptors is pieced together by the brain to form an image of the world around us. The rest of the eye is designed to focus light onto the retina in the most efficient way possible. Logically, you would expect, therefore, that the eye would be designedso that nothing blocked light from reaching the retina. And yet, in the mammalian eye, the nerves and blood vessels connecting to the rods and cones protrude outwards in front of them. In order to connect back to the brain, the nerve fibres must then break through the wall of light receptors, creating a blind spot where they join the optic nerve.

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Reasons Why Evolution is True Part IV:
Galapagos Finches

For most biologists and reasonable people, evolution is FACT. In as much as gravity could be said to be fact. However, for those who deny the existence of evolution, the difficulty of observing its occurrence in real time is proof enough that it doesn’t exist. There are a few key examples of evolution in action, however, and during these short essays I have been detailing some of them. One of the most famous examples is that of the Galapagos Finches, which inspired Darwin as he formulated his ground-breaking theory.

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Reasons Why Evolution is True Part III:
Ring Species

One common argument proposed against evolution is that we cannot see speciation in action, and thus cannot know for certain that it happens. To say that this claim is false is an understatement. Artificial selection, both in terms of the range of domestic species produced by humans over the last 10,000 years, and artificially selected laboratory populations of bacteria, insects and small mammals, certainly go a long way to prove that natural selection and speciation are possible. But does it occur in nature?

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Reasons Why Evolution is True Part II:
Parasitoid Wasps

Parasitoid wasps are a little known, but extremely prolific group of wasps, who provide one of the best examples of evidence for evolution that I’ve come across. Parasitoid wasps have a particularly gruesome way of life. They make a living by laying their eggs inside the larvae of another insect, often a caterpillar. As the young wasp develops, it devours the host from the inside out, eventually emerging and killing the host.

Parasitoid wasps are found in 37 different families of a single order, the Hymenoptera, which contains all bees, wasps and ants. There are thousands, maybe even millions of species of parasitoid wasp, each preying on a different host, utilising a different set of tactics to subdue their victim. Many parasitoid wasps are considered to be beneficial to humans because they kill garden pests such as aphids. But this is not the important part of the story.

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