Chimera, Hybrids & Half-Breeds
What is a chimera?
Chimera, sometimes spelled chimaera, have long been a part of myth and legend. The classic chimaera was a terrible, fire-breathing creature that was a fusion of a lion, goat and snake. The word chimera actually has its roots in the Greek and refers to a female goat. The term chimera has evolved to include any beast that possesses traits of two or more creatures. There are countless chimeras throughout literature in nearly every culture and this human imaginary creation has now become a scientific reality in the Muggle world!
A chimera can be produced through organ transplant, for example, where the organ and its cells and tissues are transferred from one individual to another. This blending of organisms has led to today’s use of the word chimera, which is a fusion not of different species, but of different individuals, resulting in a single organism with genetically distinct cells. Through a fusion of two or more fertilized eggs, a chimera is comprised of groups of different cells, each of which has a different complement of genes. Basically, this means two or more zygotes fused together into one organism during pregnancy. With the advent of genetic engineering, there has been a great deal of interest in producing chimeras that would have beneficial gene combinations. The study of chimeras can also help shed light on genetics by observing how possessing different populations of genetically varied cells affect organisms.
There have been interesting cases of chimeras in nature that sound like they have leapt from the pages of literature, including that of “half-siders.” Some organisms have been discovered where each side appears to have originated from a different organism. Pictured is a cardinal discovered that is half female and half male. This must have occurred where a female zygote fused with a male zygote early on in development and resulted in this individual who is half of each gender. This has also been seen in amphibians, reptiles, crustaceans and even mammals. A cat (or maybe a kneazle or kneazle-cat hybrid?) has made news as it is suspected that it follows this same pattern. It is still unclear as to whether it is truly a merging of two different fertilized eggs or just an individual who received the color patterns in a unique way. But the different color eyes certainly make us question how it came to look the way it does!
What are halfbreeds?
The word chimera should not be confused with the idea of a hybrid; many people see Fantastic Beasts that consist of anatomical structures from different organisms as a result of a mating between different species, or a halfbreed. But a chimera in the biological world is actually a single species, just being made of different cells from a merger of two or more fertilized eggs. A hybrid, on the other hand, is the result of a breeding between two different species that are similar enough to produce a viable offspring. One of the most famous hybrids, called a mule, is the result of a union between a horse (Equus ferus caballus) and donkey (Equus africanus asinus). This new hybrid offspring is possible because the horse and donkey are similar enough to produce it. The problem, however, with a mule (E. ferus caballus x E. africanus asinus) is that it is usually sterile, unable to produce its own offspring to produce a new generation. Why is this? The most generally accepted theory is that horses possess 32 pairs of chromosomes (2n = 64) where donkeys have 31 pairs of chromosomes in each body cell (2n = 62). The resulting hybrid offspring therefore would have 63 chromosomes, an odd number halfway between the two parents’s cells. There are hybrids, however, that can produce fertile offspring, but only because they are presumably genetically closer than that of the horse and donkey. Rowling sometimes refers to hybrids as “halfbreeds,” a term that some creatures like centaurs take great issue. Centaurs are not a mixture of two species; centaurs are, indeed, their own genetically distinct species with their own set of genetic information. However, halfbreeds, or hybrids, do exist in the Magical World, as Hagrid himself is a product of two different species, half giant and half human. Muggles, however, since they are so genetically different than any other species to which they are related, have no apparent hybrids today.
What is a species?
Discussions like this always lead to one of the most important questions in biology: what is a species? The biological species concept states that a species consists of members of living populations that may interbreed in their natural environment. Although an individual’s appearance is helpful in identifying species, it does not truly define the species. Today, genetics is critical in truly identifying a species to trace the evolutionary relationships between one species and another. The most popular and accepted definition of a species is a group of organisms similar enough to produce fertile offspring. These individuals must be isolated from one another but this does not simply mean being separated by geography. Organisms who live in the same area can be reproductively isolated from each other because they occupy different niches or have different preferences.
For example, Rowling writes about the different types of dragons. There was talk of hybrids between the different dragon types to produce specific traits, a process called selective breeding much like that of today’s dog and horse breeding. But why have these dragons not interbred without the help of witches and wizards? Depending on the circumstances and species, a number of isolation types could be in play here. An obvious isolation type at play could include geographic isolation. The Antipodean opaleye would not meet a common Welsh green as they are separated by a great span of land and water that keeps them from interbreeding. But what about a breeding between the Hebridean black and common Welsh green? They are both native to Great Britain so can’t they produce a viable offspring? Even without geographic barriers, they can still be reproductively isolated from one another: they could be behaviorally isolated where they don’t quite understand the courtship behavior of the other species, or they could be temporally isolated because they have different breeding seasons that don’t coincide. Another barrier to producing a viable offspring could be like that of a mule, called hybrid sterility. These two species may produce a hybrid dragon but it may be sterile. Much more information would need to be gleaned through research and data collection to know for sure.
Some questions to consider…
Ligers, sometimes referred to as tigons, are the result of a breeding between a lion and tiger. These have never been produced in the wild. What reason(s) do you think exist that keep ligers from becoming a reality in nature?
Dolores Umbridge, during her short stint as the High Inquisitor at Hogwarts, called the centaurs she encountered in the Forbidden Forest as halfbreeds.
Why were the centaurs justifiably offended? Why is it thought that kneazles can breed with regular housecats? What does this mean?
Explain why the Chinese Fireball dragon is not likely to produce offspring with the Hungarian Horntail.
It is said that hippogriffs like the famous Buckbeak are related to griffins, a fantastic beast with the body of a lion, the head and wings of an eagle, and an eagle's talons on its front feet. Do you think they could hybridize? What makes you think this way? What other information might you need to answer this question?