Could Evolution Ever Yield a ‘Perfect’ Organism?

By Nathaniel Scharping | December 16, 2015 3:48 pm
evolution

(Credit: livinglegend/Shutterstock)

It’s a crazy world out there, and if an organism wants to survive, it had better have the right tools for the job.

From anteaters to chameleons, animals have gained some pretty useful features over time, helping them to adapt to their environments and beat out the competition. Driving all of this diversity is natural selection, or the process by which beneficial mutations in genomes are identified and promoted, enabling organisms of all stripes to live longer, mate more often or perhaps just look weirder.

What’s the end game in terms of evolution though? Is there a “perfect” form that all organisms are working and evolving toward? Is there an end game? The notion of evolutionary perfection, while enticing, is likely a myth say researchers at Michigan State University. Led by Richard Lenski, a team of scientists has been observing a long lineage of E. coli bacteria for almost 28 years.

Longest-running Experiment

Encompassing over 60,000 generations of bacteria, the Long-Term Evolution Experiment is the longest continuous look at how a population of organisms evolves in a fixed environment. Put in human generational time scales, this would be about 1.8 million years, or roughly the length of time Homo sapiens has existed as a species. But for bacteria, even 60,000 generations is a small amount of time when considered against the billions of years they’ve been around.

The Long-Term Evolution Experiment is quite simple in design: Twelve separate populations of identical bacteria in identical growth mixtures were allowed to multiply and grow. Every day since 1988, one percent of each population has been transferred to a fresh flask of growth medium, allowing them to proliferate unabated at a rate of about 6.6 generations per day. A sample is frozen every 500 generations, or roughly every 75 days, to preserve a historical record of the bacteria. The bacteria are also periodically tested to determine how their level of fitness, measured by their rate of reproduction, has changed.

Thousands of Mutations

And change they have. Over the years the bacteria developed thousands of mutations, including one species that gained the ability to metabolize citrate. But most importantly, the bacteria have kept on evolving. Even after 60,000 generations, the bacteria are still showing fitness gains when compared to previous generations, and they show no signs of stopping. The researchers published a paper in 2013 following generation 50,000, in which they hypothesized that the increases in E. coli fitness correspond to a power law model, rather than a hyperbolic function. By their nature, hyperbolic functions have a limit, meaning that growth stops after a period of time. By contrast, a power law function will increase infinitely.

If bacterial growth follows a power law model as the researchers assume, this implies that while increases in fitness slow over time, there is no upper limit. Their newest findings, published Wednesday in the journal Proceedings of the Royal Society B: Biological Sciences, bear out this hypothesis, showing that the line of best fit for bacterial evolution matches much more closely to, and even exceeds, a power law model. There is no end game for evolution.

In Theory Only

While this seems to be the logical conclusion of their experiment, Michael Wiser, a co-author of the study, was quick to point out that infinite evolution likely exists only theoretically, as has been argued by some critics.

“Our general response to that has been that there is probably some theoretical limit. There could be an idealized cell that is limited solely by the diffusion of sugar through the liquid, and that they can’t grow any faster because they can’t physically get sugar into them any faster than they do,” he said. “But the thing is, we are so far from being at that point, that although that would be a theoretical upper bound…we are so far from it that it is not even relevant.”

To demonstrate this, he cites calculations the lab did carrying the experiment forward to the day when our planet is expected to be consumed by the sun. Given their current doubling rate of about 40 minutes, the researchers calculate that billions of years of evolution would allow the E. coli to double in about eight minutes.

“Although we’re saying that improvement will keep going on over indefinitely long periods of time, the reality is that improvements scale with the logarithm of time,” says Wiser. “So as you get better and better, it takes longer and longer for a particular improvement’s value to be visible.”

In Reality

Wiser also counterpointed these incredible assumptions with a reminder that evolution on Earth occurs under very different circumstances than in their experiment, which assumes a fixed environment. In the real world, evolution is constantly updating us to an ever-changing environment, meaning that what may qualify as ideal today could be harmful tomorrow.

“The reality is that what would be perfection is going to depend on lots and lots of circumstances. So as the populations adapt and you get different mutations arising and sweeping through the population…you’re going to have different sets of things that are beneficial and deleterious at different times along the evolutionary trajectory,” he said.

In the end, what the Long-Term Evolution Experiment highlights for us is not that evolution is infinite, or that perfection is unattainable, but that evolution is an ongoing process and an integral part of our existence. The planet is always changing, and the effects of human development are causing environmental fluctuations at unprecedented rates

Faced with an unsteady future, most species, including humans, are struggling to catch up. While evolving past climate change entirely is likely impossible, some species have already begun to change. Tawny owl feather colors, for example, are changing to match a snowless landscape, and pink salmon in Alaska are migrating earlier in response to warmer water temperatures.

Wiser wants us to remember that evolution is constant — it is literally a part of our DNA. The humans of yesterday looked and acted differently than we do, and our descendants will possess traits that we don’t have.

“That’s one of the driving things here, that evolution is this ongoing process. We do see evolution in action as it’s going forward. People usually think about evolution as this historical thing that took place and that’s why things are what they are now, and don’t think about the fact that evolution is still ongoing in nature right now, that things are adapting to whatever environment they are exposed to.”

CATEGORIZED UNDER: Living World, top posts
ADVERTISEMENT
  • Erik Bowen

    The closest common thing to a perfect large organism was the shark until people came along….

  • http://www.mazepath.com/uncleal/qz4.htm Uncle Al

    Begin by knowing the difference between accuracy and precision. Evolution is very good at accuracy, very poor at precision. “Faced with an unsteady future” ever since the Earth aggregated, mediocrity is a vice of the doomed. So has it ever been. Viam sapientia mundi, per quam pervenitur.

    The most successful life forms are beetles and tapeworms, opportunity and security, respectively. One eats a lot of crap to be secure.

  • http://www.RNA-mediated.com jvkohl

    Serious scientists have linked atoms to ecosystems in all living genera via nutrient-dependent RNA-mediated events that link physics, chemistry, and conserved molecular mechanisms from epigenetically-effected cell type differentiation to supercoiled DNA that protects organized genomes from virus-driven entropy.

    Tractable changes in base pairs and amino acid substitutions that stabilize DNA have been linked from nutrient energy theft for replication of the influenza virus to all pathology.

    The obvious links to pathology are being explored in the context of the “Precision Medicine Initiative” because testing already is available (and Medicare approved) to determine which nutrient energy dependent SNPs and amino acid substitutions contribute the most to the organized genomes of specific modern human populations and species-specific changes in different people.

    Welcome to the real world of science that people like Uncle Al know nothing about. A simple search for “RNA mediated” will provide you with enough information to eliminate all ridiculous theories from your perspective on health vs pathology.

  • http://www.RNA-mediated.com jvkohl

    Re: “…infinite evolution likely exists only theoretically, as has been argued by some critics.”

    The arguments of the critics have been supported by experimental evidence. The evidence linked weekend evolution of the bacterial flagellum from nutrient-dependent ecological variation to the pheromone-controlled physiology of reproduction and changes in cell type differentiation linked to the de novo creation of a functional structure of irreducible complexity.

    Thus, infinite evolution and evolution exist only theoretically because serious scientists have linked atoms to ecosystems in all living genera without any ridiculous theories.

  • jimgrot

    -the perfect organism is one with the ability/propensity to mutate successfully in close after-step with environmental change while keeping a reasonable legacy to the previous form and which is generalist enough to survive long enough in new environments for mutations to occur

    • Doug

      That sounds like a vote for viruses.

  • Bren W

    Too bad natural selection has been ruined for the human race, there might have been a chance for humans to evolve to something better.

    • dogrt

      Better at making children. Nothing else. So, not “too bad” at all.

    • nice_trousers

      what are you talking about? how has natural selection been ruined?

  • http://rambansal-the-theosoph.blogspot.com Ram Bansal, the Theosoph

    ‘perfection’ can’t be defined for being a pure hypothesis, hence reaching perfection is out of question.

  • Barrasali Ahmed

    I do not agree with the assumption that our ancestors were different from us, like they had different enzymes or hormones. Bacterial communities in different environments act differently. you can never predict which cell will live and which one will die. In humans or other complex organisms you can guess which individual will win and which will lose.

  • duelles

    I’m here after 4billion or so earth years. I must be the perfect organism for right now and right where I am. . . Along with my face mites and intestinal bacteria.

    • Private_Eyescream

      The face mites thank you for being a vast world upon which they can exploit you for easy chemical energy functions. Of course depending on computational limits (number of gigaflops per calorie emitted) the optional direction for hyper intelligent creatures is to “go small”) with sim-universes being ran on a networked mass of copy-bodies (statistically high chance of no notable data loss when individual copy-bodies are deactivated).
      What are notable copy-body nodes? Insects, bacteria, viruses, ever-smaller dust mites (scalar computational dust mite parasites living on already smaller dust mites). The smarter intelligences would not limit their computational copy-body nodes to just one species of insect or bacteria or dust mite, but they would PREFER STRONGLY that the prime network distribution nodes are highly durable for long term usage (“WOOLY BEAR” trehalose-mastering organisms which are very high-survival micro-creatures). Think of the distributed filesharing networks or crypto-currancy you use. Although individual home computers can keep the whole thing running, massive internet server farms help tremendously and you want those Prime Nodes to be rather durable. The same logic applies to sim-universe creatures. Look for durable creatures that survive pretty much everything (extremophiles) and there you find your sim-universe nodes. A bacteria that eats sulfur and farts sulfides, but does so very slowly? Everybody has to have long-term slow-function backup nodes as much as they love high-speed faster energy using E-Coli.

      A computational sim-universe does not have to resemble, inside itself, anything we are familiar with. It could resemble 1950’s America, but that is up to any particular simulated-intelligence. As form & function are no longer chemical limitations for the in-sim intelligences. Even external time passage in the “matter-verse” would be fairly irrelevant to the simulated minds inside it so long as the “sim-verse” functions tolerably. A sun that dies in 5 billion years would not be an issue so long as gigaflop computations which continue the function of the sim-universe remain at acceptable limits versus “real time”. Of course, this is old hat information for any sane human with a 150-IQ. The biggest problems for us “chemical reaction creatures” is when the “sim-universe” lifeforms do their regular “quality of computation” checks on their copy-nodes of various scales to see if our lifeforms are “still up to task” or “need fixing or junking”. For some folks, I have horrified them, others I have merely confused, but how useful are your scalar computational functions operating I ponder?

  • Dan Lipford

    “…billions of years of evolution would allow the E. coli to double in about eight minutes.” means, literally, the each E. coli or all E. coli collectively would double in some unspecified way or thing in about eight minutes, and the “unspecified way” part of that makes that statement dissatisfying – and functionally meaningless. Surely the researchers and the author(s) had some point that they were trying to get across. Wish they’d have shared it with me via specificity.

  • Private_Eyescream

    The most evoluntionarily advanced house fly is still limited by brain size (limited by body size and the core chemical reactions therein) and chemical energy sources (a housefly that could exploit microwave radiation to augment chemical energy function would have a massive reproductive advantage until it killed or significantly disrupted the creators of ambient microwave emissions – humans that use microwaves for communications).

    The true theoretical energy limit is first chemical, then ambient radient emissive energy, then atomic, then antimatter, then hyper directional sources. Much like civilizations do when they scale up their energy needs.
    Yet a hyper intelligent housefly will die if its physical power storage is too small and the exploited energy source stops transmission or transition to a lower energy state. Therein lays the obvious, any hyper intelligent species will need high energy emission radient power sources (like solar masses which are long-lived) to exploit to continue functioning and they will be very reluctant to destroy those previous-stage energy sources even if they’ve already transitioned to a better power supply. Enen creatures that go into high efficiency (no longer reliant upon physical body functions for individual intelligences) computational patchwork universe simulations will keep the old power sources running as “fallback options” in case of the unpredictable factors. The big question is how tolerant they are of lesser intelligences exploiting these “easy meal” power sources as they move up the power law ranges of easily exploitable transitional energy domains.

  • surgeen

    Like the author says in the last section evolution is adapting to the environmental changes. Any species’ perfection is limited by that of the environment it is in.
    As for human species, evolution has been so tampered by the pharmacies that faulty genes are being reproduced, and (due to the resource scarcity) at the expense of the good thinking ones’ genes who tend not to contribute to population.

  • jimgrot

    Always be sure to consider that evolution is not directed and operates with no path in mind. Whatever changes and allows a thing to pass on its altered genes (instead if dying) is where evolution goes. If changes might appear backwards but if the changes help survivability in the current circumstance then that’ll be what we see as evolution in that case.

  • Adrian Holmes

    I hate it when articles begin with a sensationalized headline, especially with this one. Of course it wouldn’t yield a “perfect organism” it doesn’t work that way! It’s not until you get to the end where it says, “…that evolution is infinite, or that perfection is unattainable, but that evolution is an ongoing process and an integral part of our existence.” Oh, okay, so why didn’t you start out with that?

  • Wan Fung Anthony CHAN

    The article in general is sound, but please, please and please don’t play with something that there is no one in the world yet scientifically defined and established….. which is the reality of human consciousness….. QUOTE: evolution is an ongoing process and an integral part of our existence. The ultimate reality of our existence which is found by consciousness which is known very little, so these two thing, evolution and consciousness, even if it is related, but they are of different domain or i don’t know may be paradigm. Which is for example, basic human emotion as jealousy, that you will no consciously think that if you spouse being pry by another person, so that your investment evolutionary will be loss, but instead, you in the other paradigm, in which resort to moral…… or grieve or unhappiness. So, don’t play with the concept you don’t understand.

NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

D-brief

Briefing you on the must-know news and trending topics in science and technology today.
ADVERTISEMENT

See More

ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Collapse bottom bar
+