But here was a bug killing a British soldier back in that already had resistance to that anti-bacterial substance, penicillium.
Horizontal gene transfer is essentially sideways heredity. It can even go from one kingdom of life into another, sideways, across great barriers. That was thought to be undoable.
In fact, genes can go sideways across vast species boundaries. For instance, a gene for resistance to one kind of antibiotic in one form of bacteria, like staphylococcus, can move sideways into another, completely different form of bacteria, say, E.
This can happen not just in bacteria but also in animals, plants, and higher organisms, generally as a result of infection or parasitism.
One example is a form of transposon. Big, complicated word. But scientists have discovered that these things can also jump from one creature to another, and even from one species to another.
One transposon has been given the name space invaders. It seems able to pass, for instance, from a reptile into an insect or from a possum into a rat, by way of something called a kissing bug, an insect that, when sucking blood, sucks in some of this transposon. The transposon then moves from one species to another and becomes part of the heritable genome of that new species.
There are two phases in classic Darwinian evolution. First, there is the arising of variations from one creature to another or one individual population to another.
That was thought to occur incrementally, in very slow stages, by mutations in the genome. Once there are variations among individuals, natural selection, the survival of the fittest, acts upon those variations. But horizontal gene transfer has revealed that nature does sometimes make leaps, whereby huge lumps of DNA can appear in an individual or population quite suddenly and then natural selection acts on them. That can be a very important mechanism in the evolution of new species.
We now realize, because we can sequence genomes, that we have great populations of bacteria living within us. In fact, there are hundreds, if not thousands, of different kinds of bacteria that live benignly within our guts, armpits, ears, noses, pores, or on our skin.
This is known as the human microbiome. The maintenance of that ecosystem of microbes is essential to human health, which is one reason why the over-use of antibiotics can be a bad thing. Most antibiotics tend to be broad range. We now understand that we humans, along with most other creatures, are composites of other creatures. Not just the microbiome living in our bellies and intestines, but creatures that have over time become inserted in our very cells. Every cell in the human body contains, for instance, little mechanisms that help package energy.
Those are called mitochondria. We now realize that those mitochondria are the descendants of captured bacteria that were either swallowed by, or infected, the cells that became complex cells of all animals and plants. Likewise, 8 percent of the human genome, we now know, is viral DNA, which has come into our lineage by infection over the last million years or so. Some of that viral DNA is still functioning as genes that are important for human life and reproduction.
CRISPR is an acronym for a gene-editing tool discovered in the last years that is very powerful and inexpensive. With it, scientists can now edit genomes, delete mutations or insert sections of new genes. It promises a lot of wonderful medical possibilities and a lot of really troubling moral and societal choices.
No one gave a hoot about his work. Soon scientists had figured out that it was DNA that held the information that gives you your many traits, and in Watson, Crick, and colleagues finally gave it a shape: the famous double helix.
We now know that inheriting traits has nothing to do with gemmules mixing together. We of course get our DNA, which contains genes, from both our mother and father. But these are combined in unique ways at each conception , leading to variations even among siblings.
So these mutations, combined with genetic shuffling at birth, drive variations and therefore evolution: Some individuals are born with traits that may suit them better to their environment, which boosts their chances of surviving and breeding and passing those genes to future generations.
And isn't it at least a little bit comforting to be reminded that even the greatest minds in history can muck things up? It sure is for me, considering that up until recently I didn't know that avocados were fruits. I mean, who saw that coming? Browse the full Fantastically Wrong archive here. Have a crazy theory or myth you want me to cover?
Darwin, C. London: John Murray. Put simply, changes in quantity have produced a change in quality, and in my view we live in a different world now regarding our understandings of life and its meanderings. Scientists across a broad range of disciplines genetics, taxonomy, paleontology, etc.
There is grandeur in this new view of life, so why force it into the Procrustean bed of nineteenth-century theorizing? Your friend, Jim. Further Reading :. Science, History and Truth at the Faculty Club. Thomas Kuhn Wasn't So Bad. Mind-Body Problems free online book, also available as Kindle e-book and paperback. Don't tell the creationists, but scientists don't have a clue how life began.
The views expressed are those of the author s and are not necessarily those of Scientific American. For many years, he wrote the immensely popular blog Cross Check for Scientific American. Follow John Horgan on Twitter.
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