Tag Archives: Common Ancestor

New study: another example of convergence, this time for geomagnetic navigation

We have to start this post with the definition of convergence in biology.

In evolutionary biology, convergent evolution is the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.

It is the opposite of divergent evolution, where related species evolve different traits.

On a molecular level, this can happen due to random mutation unrelated to adaptive changes; see long branch attraction. In cultural evolution, convergent evolution is the development of similar cultural adaptations to similar environmental conditions by different peoples with different ancestral cultures. An example of convergent evolution is the similar nature of the flight/wings of insects, birds, pterosaurs, and bats.

All four serve the same function and are similar in structure, but each evolved independently.

And now, Evolution News has a story about a new discovery.

Turtles have the ability to navigate by sensing magnetic isolines:

Science Magazine gives a brief review of the findings:

Much like shifting sand, magnetic fields slide slightly over time, and their strength also increases as one moves away from the equator, akin to latitude.This property gives each stretch of coast a unique geographic marker, known as an isoline. The team found that in years when these magnetic isolines moved apart, the turtle nests spread out over a larger area — by 1 or 2 kilometers. Conversely, when isolines converged, the nests squeezed into a smaller patch of beach, suggesting the turtles follow shifting magnetic tracks to their favorite nests. The findings also argue that a magnetic address is imprinted on loggerhead turtles at birth to point the way home.

But so do salmon, and other birds, fishes and mammals:

Remarkably, salmon show this same ability. Brothers and Lohman write:

In a previous study, the migratory route of salmon approaching their natal river was shown to vary with subtle changes in the Earth’s field. Whereas the endpoint of the salmon spawning migration was presumably the same regardless of route, our findings demonstrate for the first time a relationship between changes in Earth’s magnetic field and the locations where long-distance migrants return to reproduce.

Joining the contenders for this skill set are more unrelated animal types:

… our results provide the strongest evidence to date that sea turtles find their nesting areas at least in part by navigating to unique magnetic signatures along the coast. In addition, our results are consistent with the hypothesis that turtles accomplish natal homing largely on the basis of magnetic navigation and geomagnetic imprinting. These findings, in combination with recent studies on Pacific salmon, suggest that similar mechanisms might underlie natal homing in diverse long-distance migrants such as fishes, birds, and mammals.

So here we have a highly-precise navigational ability, able to cue on very faint properties in the earth’s magnetic field, then on olfaction, and possibly on “other supplemental local cues” to find home across thousands of miles. The sensory “instruments” involved are integrated so that they are able to coordinate their functions for the same goal. Furthermore, the baby turtles, with their tiny brains, must have the ability to memorize the natal signatures of odors and magnetic field properties at birth, then recall those memories years later as large adults. (Sea turtles return about every two years to lay eggs.)

That would be a conundrum enough to explain by unguided processes like natural selection. But then, adding to the difficulty for Darwinism, similar abilities are found in distantly related animals like fish, birds, and mammals. Even if a Darwinian could show a possible line of descent from fish to mammal, the abilities involved would have been lost and regained multiple times, because not all fish, birds, and mammals use magnetic navigation. Given the complexities of the sensory systems involved, this would represent a case of “convergent evolution” on steroids. If the origin of this capability in one type of animal is highly implausible by mutation and selection, how about four times or more?

A design perspective, by contrast, would expect that unrelated animals on a common planet would share similar capabilities for their needs. The earth’s magnetic field is global. It isn’t surprising that very different animals would be designed to use that feature of the earth.

How can it be that animals that have no recent common ancestor can have evolved this remarkable ability independently? The best explanation of this convergence is common design, not common descent.

More posts on convergence

Peer-reviewed journal notes that Ida is not part of human ancestry

This story comes to me from Lone Wolf Archer.

Probably the two best peer-reviewed science journals in the world are Science and Nature. Well, Nature is now reporting on a new piece of research just released showing that the Ida fossil, which was touted by Darwinists as THE MISSING LINK, is actually not a part of human ancestry at all. It’s related to lemur ancestry!

Here’s the Nature story:

A 37-million-year-old fossil primate from Egypt, described today in Nature1, moves a controversial German fossil known as Ida out of the human lineage.

Teeth and ankle bones of the new Egyptian specimen show that the 47-million-year-old Ida, formally called Darwinius masillae, is not in the lineage of early apes and monkeys (haplorhines), but instead belongs to ancestors (adapiforms) of today’s lemurs and lorises.

Lone Wolf Archer has more here, including a link to a longer story that explains the details.

Is universal common ancestry based on established facts?

Casey Luskin wrote a wonderful article called “A Primer on the Tree of Life” that will help you to consider whether universal common ancestry is true.

Excerpt:

Evolutionists often claim that universal common ancestry and the “tree of life” are established facts. One recent opinion article argued, “The evidence that all life, plants and animals, humans and fruit flies, evolved from a common ancestor by mutation and natural selection is beyond theory. It is a fact. Anyone who takes the time to read the evidence with an open mind will join scientists and the well-educated.”1 The take-home message is that if you doubt Darwin’s tree of life, you’re ignorant. No one wants to be ridiculed, so it’s a lot easier to buy the rhetoric and “join scientists and the well-educated.”

But what is the evidence for their claim, and how much of it is based upon assumptions? The truth is that common ancestry is merely an assumption that governs interpretation of the data, not an undeniable conclusion, and whenever data contradicts expectations of common descent, evolutionists resort to a variety of different ad hoc rationalizations to save common descent from being falsified.

Here are two of the four evidences he looks at:

Molecular phylogenies

…the cover story of the journal New Scientist… titled, “Why Darwin was wrong about the tree of life.” …reported that “The problem was that different genes told contradictory evolutionary stories.” The article observed that with the sequencing of the genes and proteins of various living organisms, the tree of life fell apart…

You get completely different molecular phylogenies depending on which gene or protein you analyze from the organism. If UCA were true, all the genes and proteins would have to give similar molecular phylogenies. Casey also addresses horizontal gene transfer.

Convergent evolution

One data-point that might suggest common design rather than common descent is the gene “pax-6.” Pax-6 is one of those pesky instances where extreme genetic similarity popped up in a place totally unexpected and unpredicted by evolutionary biology. In short, scientists have discovered that organisms as diverse as jellyfish, arthropods, mollusks, and vertebrates all use pax-6 to control development of their very distinct types of eyes. Because their eye-types are so different, it previously hadn’t been thought that these organisms even shared a common ancestor with an eye.

Here, you have the same gene being used for the same function in different organisms that do not share a common ancestor.

Homologies and Morphological phylogenies

Casey goes on to look at the evidence from homologies and the disparities between molecular phylogenies and morphological phylogenies, (e.g. – Cytochrome B). Casey’s article is worth looking at, especially if you have never considered the case against universal common ancestry.