Today’s New Reason To Believe

David H. Rogstad, Ph.D.

The intricate design present in biological systems never ceases to amaze. A few months ago I wrote about molecular motors present in biological cells and how they are giving insight to researchers in nanotechnology, either providing them with improved motor designs or actual devices to use in driving man-made miniature machines. In addition, Fuz Rana’s recently released book, The Cell’s Design, is filled with examples of similar biochemical design taken from all areas of cell function.

Scientists have known for some time about the design of the flagellum, the tiny corkscrew-like propeller and motor that some bacteria use for locomotion. With a stator, rotor, shaft, bushings, and a universal joint, this microscopic motor looks a lot like those that engineers design for running our home appliances, such as refrigerators and vacuum cleaners.

Recently, researchers discovered that the flagellum motor in the bacterium Bacillus subtilis also has a clutch that allows the rotor to disengage. Reporting in the latest issue of Science (see a press release here), a research team from Indiana University Bloomington and Harvard University led by biologist Daniel Kearns learned of this capability by accident. Kearns and colleagues were actually interested in how B. subtilis ceased its wandering activity when it took up residence in stationary assemblages called biofilms. The stability of a biofilm can be jeopardized if the flagella continued to spin. Understanding biofilm formation may prove useful in combating infections.

When the scientists realized that a particular protein, EpsE, was involved in repressing the flagellar motion, they proposed two possible explanations. One was that the EpsE acted as a brake, locking up the moving and nonmoving parts; the other was that EpsE worked like a clutch, disengaging the parts from each other. They were able to devise an experiment where the tail end of the flagellum was attached to a glass slide. They observed what happened in the presence and absence of EpsE. Since the cells stopped but could still rotate passively in the presence of EpsE, they concluded that it functioned as a clutch.

“We think it’s pretty cool that evolving bacteria and human engineers arrived at a similar solution to the same problem,” said Kearns. “How do you temporarily stop a motor once it gets going?”

Their press release concluded: “The discovery may give nanotechnologists ideas about how to regulate tiny engines of their own creation. The flagellum is one of nature’s smallest and most powerful motors—ones like those produced by B. subtilis can rotate more than 200 times per second, driven by 1,400 piconewton-nanometers of torque. That’s quite a bit of (miniature) horsepower for a machine whose width stretches only a few dozen nanometers.”

While these scientists attribute this remarkable capability to an evolutionary process, in light of the superior design in evidence, it seems far more likely that it reveals the hand of a Master Designer.

Posted by Fazale ‘Fuz’ Rana, Ph.D.

Neanderthal Speech Gene May be Due to Contamination

Nobody really likes a potty mouth, including anthropologists. But it looks like these scientists will have to put up with “contaminated” language from Neanderthals, at least if the results of new work are valid. It appears as if the recovery of the so-called language gene from the remains of Neanderthals is not authentic, but instead may be due to contamination from human DNA.

The question of whether or not Neanderthals possessed language capacity has precipitated much controversy. Anatomical studies are ambiguous towards this end. (See Who Was Adam? for a detailed discussion.) To help resolve this issue a team from the Max Planck Institute turned to ancient DNA analysis to probe for the language gene in the Neanderthal genome.

In 2001, a research team from the United Kingdom reported that mutations in the FOXP2 gene cause severe language disorders. Presumably the FOXP2 protein plays a key role in controlling the development of brain and facial structures that support aspects of human language capacity.

An initial evolutionary analysis of the FOXP2 gene, conducted in 2002, indicated that the human variant arose about 200,000 years ago. Subsequent work, published later that year, placed the origin of the human FOXP2 gene at about 100,000 years ago. From an evolutionary standpoint, this is well after the time that humans and Neanderthals allegedly split from a common ancestor. Accordingly, Neanderthals should not possess a human-like FOXP2 gene and, therefore, language ability.

However, to everyone’s surprise, the team from the Max Planck Institute did isolate the human variant of the FOXP2 gene from a recently recovered Neanderthal specimen. This result was interpreted by some as evidence that Neanderthals had language. If so, it creates problems for the RTB human origins model, which predicts that Neanderthals and other hominids should behave in nonhuman ways, and, therefore, should not have the capacity for language.

Did Neanderthals possess language ability? At the time that the recovery of the Neanderthal language gene was announced I wrote:

The very real possibility exists that this result stems from contamination by human DNA. Clearly, the research team went to painstaking efforts to avoid contamination. Anthropologists suited up in clean room gowns and face masks to excavate the Neanderthal remains using sterilized tools. They designed the extraction protocol to avoid isolating any human DNA and ran the appropriate controls to ensure the Neanderthal DNA samples had no human contamination. In spite of these heroic efforts, the possibility of contamination cannot be ruled out. The team from the Max Planck Institute introduced contamination into the Neanderthal genome sample they were previously working with and wrongly interpreted this as evidence for human-Neanderthal interbreeding.

It looks like my initial assessment was right. A research team for the University of Chicago re-assessed the likelihood that Neanderthals possessed the human variant of FOXP2 by looking at the genetic variation associated with this gene among modern human populations. They concluded that the scenario proposed by the Max Planck workers—namely the human variant arose prior to the time that Neanderthal and human lineages diverged from a common ancestor—is inconsistent with the genetic patterns observed among modern humans. They also estimated that the human variant of FOXP2 arose about 42,000 years ago. This result falls in line with earlier estimates, which places the origin of the human variant between 100,000 and 200,000 years ago.

The Chicago scientists suggest two possible scenarios to explain the recovery of the human variant of the FOXP2 gene from Neanderthal remains. First, humans introduced the language gene into the Neanderthal gene pool through interbreeding. They assert that if low levels of interbreeding took place between humans and Neanderthals, this could account for the appearance of the human language gene in the Neanderthal genome. This conclusion is not well supported by other studies, which have failed to find any direct evidence for interbreeding.

The other possibility is that the DNA extracted from Neanderthals was contaminated with modern human DNA. Even though the Max Planck Institute scientists took every precaution to avoid contamination and even ran controls to ensure that their samples were free from contaminants, human DNA, which is ubiquitous, could have easily made its way into the sample. The team from the University of Chicago raises questions about the effectiveness of the control samples. They assert that the controls selected by the Max Planck team do not necessarily ensure contaminant-free Neanderthal DNA samples.

It is really beginning to look like Neanderthals didn’t have language capacity after all—just contaminated language. Now I’d like to know who’s going to volunteer to wash their mouths out with soap.

David H. Rogstad, Ph.D.

“Biology is the study of complicated things that give the appearance of having been designed for a purpose.” — Richard Dawkins, atheist biologist, in The Blind Watchmaker

“Biologists must constantly keep in mind that what they see was not designed, but rather evolved.” — Francis Crick, atheist biochemist, in What Mad Pursuit

“The evidence for design is overwhelming.” — Paul Davies, agnostic astronomer, in The Cosmic Blueprint

In light of such statements, it is not a stretch to claim that scientific evidence supports the idea of design in nature. The real argument is not over the presence of design but over the source of this design. Is it the random process of mutation and natural selection, or the work of an Intelligent Designer?

I find it remarkable how often the creativity we find in nature is similar to human design—albeit, nature’s are usually more exquisite, optimal, or efficient. (See this example from nanotechnology in a previous report.)

Andy McIntosh and Novid Beheshti provide us with yet another example in biology through a study initiated several years ago at Leeds University in the UK and reported in the April 2008 issue of Physics World. The bombardier beetle is an insect commonly found in Africa, Asia, and parts of the U.S. This amazing bug can fire a powerful jet of hot, toxic fluid with pinpoint accuracy and variable droplet size in any direction up to 20 cm in distance to fight off various predators such as spiders, ants, birds, or frogs.

The bombardier beetle creates the fluid from two chemicals, hydroquinone and hydrogen peroxide, that it stores in its abdomen in a pair of combustion chambers. When threatened, it mixes the two chemicals to create a toxic mixture, which includes benzoquinone and water heated above boiling point. It then powerfully ejects the weapon toward its target.

In their study, McIntosh and Beheshti managed to replicate the process used by the beetle. They performed a series of experiments firing pulses of hot water up to distances of four meters, at the same time controlling the size of the droplets in the spray. The study was motivated by the possible applications of this technology. It could influence such things as drug delivery devices like inhalers, or the fuel injectors used in automobile engines, or the nozzles used in fire extinguishers.

Once again, nature provides inspiration for human technology. The bombardier beetle’s exquisite defense mechanism surely invigorates William Paley’s argument for the source of design in nature being a “Watchmaker” rather than random chance!