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|Biomorphs (Computing with the Amstrad)||Applications Divers|
CHRISTIAN PINDER's biomorphs give you control over evolution
LAST year on BBC 2 Dr. Richard Dawkins, a lecturer in Zoology at Oxford University, hosted a programme about the evolution of life. Richard Dawkins is also the author of The Blind Watchmaker, a book which seeks to explain evolution and natural selection in layman's terms.
Natural selection, in case you haven't heard of it, is generally accepted by scientists to be the mechanism by which life has evolved on Earth. In both the book and the TV programme Dr. Dawkins described and demonstrated a computer simulation of this process.
The program accompanying this article is a conversion of one originally written by Mike Cook for Electron User, which in turn is a simplified version of Richard Dawkins' simulation. Before getting on to the program I'll explain its background so you'll know what's going on.
The appearance of an animal or plant is determined by the genes it inherits from its parents. Genes are to be found at the heart of each cell in every living thing - including you and me.
To simplify the explanation I'll concentrate on asexual reproduction, which involves only one parent. This may seem artificial but it's common in plants and the lower animals.
Ignoring the influence of the environment, if an offspring's genes are identical to those of its parent, the two animals or plants will look exactly the same. In real life, however, genes can alter for a variety of reasons,
If a gene mutates and is passed on to an offspring, the result will be that the child looks slightly different to its parent. For instance if the gene controlling size mutated, the offspring would be larger or smaller than its immediate ancestor.
The physical alteration brought about by mutation of its genes may give the creature an increased chance of survival, and if so, it will tend to live longer and produce more descendants than its less well-endowed fellows.
Offspring with the altered gene are also more likely to survive, therefore they will tend to have more children, and as the generations progress an ever greater proportion of the population will inherit the mutation.
Eventually just about everyone will have the new gene, and the species as a whole will have evolved. The changes tend to be in small steps and accumulate into major developments over many thousands or millions of generations.
This tendency for favourable mutations to propagate and unfavourable ones to die out is known as natural selection, and is the driving force of evolution. In higher animals with long life cycles evolution is a slow process, so if you watch Fido, the next-door neighbours or grandma, you will not notice it happening.
Humans are only comfortable thinking in time scales ranging from seconds to, at most, a few lifetimes. For this reason many people find the concept of evolution difficult to accept.
Scientists working with plants or animals able to reproduce and mature quickly can observe the effect in the laboratory, but this isn't accessible to you and me. As an alternative to real plants and animals we can use the Amstrad to simulate evolution and natural selection.
The creatures we're going to observe are the biomorphs. Actually a biomorph is nothing more than the binary tree we looked at in the October 1987 issue, with a set of six genes to control aspects of it's appearance. The functions of the genes are shown in Table I together with their maximum and minimum values.
Biomorphs have a peculiar lifestyle. They go in for one-parent families and always produce litters of 12. When the parent dies, only one child reproduces and so becomes the mother of the next generation. Each daughter differs from her mum by a small mutation in one gene.
Extensive research by a team of top biologists has revealed the reason for the litters of 12: Each of the six genes can mutate up or down compared to the parent giving 12 possible children.
Armed with this information it's time to grow your own. When you run the biomorph breeder you will have the option to start at one of three points - an alien, a random point where the first biomorph will be chosen by the micro, or you can specify the genes. In this last option, you only define the first five as the sixth controls colour and doesn't affect the overall shape.
The program will put the parent at the centre of the screen and generate the offspring around it. After each daughter has been drawn you will be asked which one you would like to become the parent of the next generation. Press a key from A-L as appropriate and the whole thing starts again.
In this way you can watch these artificial creatures evolve as you apply your own rules of survival - a sort of unnatural selection.
If you want to see the current values of the genes, press Tab, then any key to continue. You can write the numbers down and use them as a starting point next time you run the program
There are many ways in which Biomorphs could be tinkered with. For example the maximum and minimum values of a gene are held in data statements and can easily be changed, or you could put in a routine to save interesting breeds to tape or disc.
If you want to know more about the subject, I recommend you read The Blind Watchmaker. It's published by Longman Scientific and Technical, ISBN 0-582-44694-5.
The book is very readable and offers a clear and fascinating insight into the way life has developed on our planet. It answers such questions as how something as complicated as the human eye could have arisen without the need for a "grand designer".
All that's left is for you to type in the program and start discovering those fabulous little biomorphs. The only bugs are the ones in cages on the screen. If the program won't run properly, track down your typing mistakes by using the checksums in conjunction with the checksum utility published in the June 1987 issue.