In the early 1900s, Thomas Hunt Morgan, Columbia University zoologist, was looking for an organism to test Charles Darwin’s theory in the laboratory. Morgan was critical of Darwin’s theory of natural selection. After learning of an easily-reproducible insect yielding hundreds of progeny every few weeks, Morgan thought that he had discovered a model by which to study evolution. Morgan was eventually awarded the Nobel Prize in Physiology or Medicine for demonstrating that chromosomes act as the carriers of inheritance in 1936.
Of the lion’s share of laboratory research, Morgan’s fruit flies became one of the most popular study models of evolution. After surviving through an unknown number of laboratory experiments, however, fruit flies are still fruit flies. “We are due for a renaissance,” said Alejandro Sánchez Alvarado, a biologist at the Stowers Institute for Medical Research in Kansas City, Missouri in an interview with Quanta Magazine science writer Emily Singer. “We have narrowed our focus to a handful of organisms that statistically are highly unlikely to encompass the gamut of biological activity on the planet.” The evolution industry is on a mission to find a new study model of evolution.
Fruit Fly Model
Morgan eventually emerged as one of the most revered biologists of the 20th century. Armed with Morgan’s laboratory fruit fly, Drosophila melanogaster, evolutionary scientists began to advance a new theory of evolution consensus. With the new theory gaining momentum, a number of new titles began to circulate including Neo-Darwinism and the Modern Synthesis Theory. The new “central dogma,” a synthesis of genetic mutations + Darwin’s natural selection, emerged as the cornerstone mechanism driving biological evolution.
While gaining scientific acceptance for the new “central dogma” within academia was a formidable challenge. Morgan had impressive results. By exposing fruit fly genetic material to toxins and radiation starting in 1908, Morgan could produce new and dramatic morphological changes.
These newly mutated fruit flies passed the changes on from one generation to the next as predicted by Gregor Mendel’s laws of genetics. A model of evolution, it seemed, could be produced in the laboratory. The results were published in his 1915 book entitled Mechanism of Mendelian Inheritance. Darwin’s origin of species theory could finally be tested and reproduced, it seemed.
A tentative consensus was eventually sealed within evolution academia following the publication of Evolution, The Modern Synthesis, by English biologist Julian Huxley in 1941. However, since the structure of DNA, was not discovered until after the war in 1953 by University of Cambridge molecular biologists Francis Crick and James D Watson, quantifying and qualifying the molecular basis of the genetic mutations remained only speculative.
The four-winged fruit flies (pictured), along with other variants, could be regularly produced with radiation-induced mutations in the laboratory, but nagging questions remained. Were these genetic mutations actually beneficial? More importantly, could the generation of successive genetic mutations give rise to a new species? A sustainable model of evolution had yet to be tested in nature.
Questions over the “central dogma” continued to plague the new theory. For example, the four-winged fruit fly aerodynamics were an awkward version of the two-winged fruit fly. Ernst Mayr, one of the 20th century leading evolutionary biologists, in 1963 was rather blunt –
“[The four-winged fruit flies] are such evident freaks that these monsters can be designated only as ‘hopeless.’ They are so utterly unbalanced that they would not have the slightest chance of escaping elimination.”
Undeterred at the time, however, geneticist Edward Lewis of the California Institute of Technology in 1978 tested the model further. Reproducing Morgan’s mutations, Lewis demonstrated that the four-winged fruit fly was actually the result of three mutations in the single large gene called Ultrabithorax. For his work, Lewis was awarded a Nobel Prize in 1995.
Facts & Reality
The four-winged fruit fly experiments permitted scientists a glimpse into the emerging new world of genetics. However, by the end of the century the prospects that genetic mutations could supply the raw materials for evolution, the “central dogma,” faced an unceremonious fate. In the words of Italian geneticist Giuseppe Sermonti,
“One spur to research on mutations was the hope that an accumulation of these might lead to a new species. But this never happened.”
In the laboratory or in nature through natural selection, Drosophila melanogaster has since never emerged as a common ancestor for any new species – as once anticipated. Today, there are no known natural populations of four-winged fruit flies in existence after more than 100 years of experimentation.
The fruit fly has not been forgotten, though, and remains a timeless example of evolution – but, for a new reason. Evolution 101 website, sponsored by the University of California, includes only two models of “speciation in action” – the spotted owl and the fruit fly. Despite a legacy of Nobel prize awards for Morgan’s mutation model of speciation, it has been replaced by Darwin’s old recycled theory of “geographical isolation” – a model based on nineteenth century logic, not science.
The evolution industry is desperately searching for a new study model of evolution.
Cellular biologist Sánchez Alvarado (pictured) of the Howard Hughes Medical Institute this summer convened a panel of experts at Woods Hole’s Marine Biological Laboratory (MBL) in Massachusetts to begin the discussion for developing a new study model of evolution with broader diversity.
“Most of the biological world lies before us unexplored and unknown,” said Jonathan Gitlin, MBL’s director of research. “If most of what we know comes from seven organisms, imagine what we would know if we had 700.”
Finding a new easily reproducible laboratory-friendly species with yet unknown, novel, evolutionary secrets is no small task. Carrie Albertin, a graduate student, while following Cliff Ragsdale, a neuroscientist at the University of Chicago, on a search for a suitable laboratory to perform experiments on her doctoral research project, encountered a scene not to be soon forgotten.
In Ragsdale’s 240-gallon tank, Carrie watched in amazement one lone octopus egg the size of a pinky nail. “Within five minutes, it hatched, looked at us, changed colors, inked and swam away,” Albertin said. “I was sold.”
Albertin is not alone. Scientists are increasingly looking at the extraordinary nature of cephalopods as a new study model of evolution. Why? The cephalopods, a group that includes octopus, squid and cuttlefish, have unparalleled uniqueness and powers. One is the power of regeneration. Cephalopods can grow new tentacles from scratch.
As invertebrates, like flies and worms, cephalopods communicate through sophisticated signals through their LED-like skin. Cephalopods are capable of performing strikingly complex behaviors without any known vertebrate nervous system counterpart.
YouTube has a storehouse of amazing cephalopod feats, from octopuses opening jars to carrying around a coconut shell as a shelter from predators. The feats of an octopus named Inky at a New Zealand aquarium made global headlines in April after slipping through a small gap in the top of his tank, scampered across the floor, slithered down a 164-foot-long drainpipe and into the sea.
Cephalopods challenge the traditional evolution paradigm of proceeding through Darwin’s “slight successive” changes – from simple beginnings in Darwin’s “warming little pond” to increasing complexity.
The cephalopod nervous system is an evolution enigma since many have no central nervous system. In the Octopus, the neurons are equally distributed into each of its eight arms. Some Octopuses species can detach an arm when attacked by a predator, leaving the detached but active limb to struggle with the predator while escaping. According to Rosenthal,
“They [Octopuses] are interesting because they evolved complexity through a completely different [yet, unknown] avenue,”
The molecular biology of cephalopods, like the central nervous system, is an even more challenging evolution enigma. Protocadherin proteins are known to be responsible for determining neuronal connection pathways. Counter to expectation from evolution theory of simple to complex, scientists have discovered 168 different kinds of protocadherins in the Octopus compared with just 58 in Humans.
This molecular problem extends to the genome. After sequencing the Octopus last summer, scientists were surprised to discover the Octopus genome is nearly as big as our own. The Octopus has 2.7 billion bases compared with 3 billion bases in Humans containing roughly 33,000 genes compared with roughly 20,000 genes in humans. Cephalopods are invertebrate, not vertebrates. Where is the evolution logic?
Ragsdale plans to tackle these evolution logistical incongruities by performing controlled gene deletion experiments – not gene mutation – that produce the different kinds of protocadherins and analyze the outcome effects on neuronal circuitry. Ragsdale’ goal is to develop a new genetic study model of evolution.
“Let’s pretend, Alvarado said. “We don’t have to stick with the traditional models.” The “central dogma,” genetic mutation + natural selection, is facing extinction within the scientific community.
Finding a new model, however, is no easy task. In the field of comparative genomics, there have been increasing incongruent evolutionary findings. In the article entitled “Squid enrich their DNA ‘blueprint’ through prolific editing” published in Science Daily, highlights the new challenge –
“One of the surprising discoveries to emerge from the young field of comparative genomics is that drastically different organisms–humans, sea urchins, worms, flies –are endowed with a more or less common set of genes. Given a similar DNA blueprint, then, how do species develop such vast differences in physical shape, size, and complexity?”
A common set of genes has emerged as an unexpected zinger for any gene-based theory of evolution, especially, the “central dogma.” As Science Daily explains –
“Contrary to the classical “central dogma” of molecular biology, genetic information does not always pass faithfully from genomic DNA to messenger RNA to the synthesis of proteins. Rather, the information can be significantly altered along the way by a variety of means, including by precision ‘editing’ at the RNA stage to fine-tune the type of proteins that will be produced.”
Despite a flood of challenges since the publication of The Origin of Species in 1859 by Charles Darwin and more than 150 years of unprecedented scientific efforts in the history of mankind to prove otherwise, the evidence examined in nature tooled with unprecedented technology continues to be compatible with the Genesis record written by Moses.
“Microscopic beings must come into the world from parents similar to themselves… There is something in the depths of our souls which tells us that the world must be more than a mere combination of events.”
Evolution, once a theory in crisis, is now in crisis without even a cohesive unifying theory.
Biological evolution exists only as a philosophy, not a science.