Spring has come incredibly early this year, since there was almost no winter (well, where I am living). It is still not warm, but very mild for the time of the year, and I am going for a walk. Everywhere, flowers are opening already, some white, some pink and some yellow. There is a whiff of a nice scent from one of the bushes.
Why is it, I think, that these flowers are beautiful for us and smell so nice? They are adapted to insects, aren’t they? So why are they attractive to us? There must be a reason for that, a reason deep in the past…
Maybe the story started about a hundred million years ago, in the age of the dinosaurs. Imagine a world with forests, with high trees and small herbs but no colorful flowers yet. I don’t know if early dinosaurs could distinguish colors anyway, but their descendants, birds, can. Their dinosaur ancestors, the theropod dinosaurs, seem to have become warm blooded at some time during their evolution. Being able to control your body’s temperature is energetically expensive but it seems to convey advantages. For example, warm blooded animals have by far less fungal pathogens since most of these where obviously unable to adapt to the higher body temperature. Whatever the reason, being warm blooded made it advantageous to have some thermal insulation, so they developed feathers.
If you look at birds today, you see that many of them are very colorful. Maybe colors became indicators of health and it became advantageous to be able to distinguish colors well in order to get a healthy mate. Based on this, colorful displays could have developed as well as an increased ability to distinguish colors.
Feathers, however, also provided a building element for wings and finally, some small feathered dinosaurs developed flight. Now fast forward a couple of million years. Birds are flying around and some of them find a source of food quite different from that of their predatory ancestors: fruits. For a tree, having its fruits eaten by a bird can be a big advantage. The bird can carry the fruit away over long distances, spreading the trees offspring over a large area. This makes survival of some of the offspring more likely in case of local disasters like fire or outbreaks of parasites. Trees of one species might now be far apart from each other in the forest as a result, and forests that might have been uniform systems consisting of only a few species turn into multi-species patchworks. For a bird, however, this is a problem because how will it find the fruits it can eat. The solution, of mutual advantage for bird and tree, is color. The fruits change their color as soon as the seed is ready to be dispersed and the food for the bird is ready. The birds, having good color vision, can spot them from a distance and disperse the seeds.
Enter the monkeys (who will turn out to be our ancestors millions of years later). They too develop color vision and this enables them to spot the fruits too. Moving through the canopy from tree to tree, they are now able to also use that source of food, the bird’s fruits. They too move over large distances on the search for ripe fruits so they become a good seed distributor for the tree as well. Some trees develop fruits that appeal to monkeys, sweet, with aromas nice for a monkey and a size adapted to a monkey’s hand and mouth. These fruits are the ancestors of the fruits we eat today since we have inherited that taste. And it looks like we have also inherited a liking for those colorful spots on the plants that indicated a rich source of food to our monkey ancestors.
Like everywhere, our forest of several tens million years ago was also home to insects. Some of them, some wasp like ones maybe, also developed a liking for these fruits. Think of wasps gnawing on plums or pears and you will get the idea. For these insects, it would have been advantageous to be able to spot the fruits at some distance, by their shape, their color and their scent. So soon (in earth-historical terms) we have fruits appealing to monkeys and we have insects that have a liking for these monkey-fruits and an ability to spot them from some distance.
And this brings us back to the flowers. The presence of fruit-eating insects provided a chance for some flowers to spread their pollen by imitating a monkey-fruit. To do so, the plant has to have a flower that is about the size, shape (from an insect’s point of view) and color of a monkey fruit, a more or less fruity scent (made up from substances chemically similar to those resulting in monkey-fruit scents) and some sugar. Since the flowers actually provided sugar in the form of nectar, some insects subsequently adapted to such flowers, giving up the fruit diet of their ancestors. The presence of such insects now gave an opportunity to more plants to develop flowers targeted at those insects. As a result, the world filled with colorful and often perfumed flowers.
So my hypothesis is that these flowers developed as imitations of monkey fruits. As such, they would not have fooled a monkey but they might have fooled an insect with its much simpler and smaller brain. Although the monkeys would not mistake these flowers for fruits, they would still have found their colors and scents attractive, and so do we…
It seems to me that there are, hidden in the history of life, lots of connections between organisms. For me, these connections add a layer of beauty and fascination to the world. If the world was just the creation of a creator, everything would be arbitrary. The created world would be conceptually “flat” and without a deep structure, without interconnections between things. The idea of a created world seems conceptually poor and bland and ugly to me.
The results of evolution, on the other hand, are not arbitrary although there is a permanent component of randomness involved in the process. Instead, because of permanent interactions between organisms, there are connections. Our liking of flowers, resurfacing in our perfumes and in the colors of our art, may be connected to the history of insects, monkeys, fruit trees, birds, dinosaurs, fungi and so on. There is a rich structure and things belong together because there is a history from which they have arisen.
These are just some hypotheses, I have not checked the scientific literature on this, just puzzled together some pieces. It might have happened this way or another (I leave that to the scientists), but however it happened, what a wonderful result!
A bush covered in white flowers and a whiff of its perfume again – spring.
(The picture is from http://commons.wikimedia.org/wiki/File:Ramphastos_sulfuratus_-upper_body-8a.jpg.)