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What do your skin, a compost pile and Lake Superior all have in common? Each of them is home to an abundance of microscopic germs, properly called bacteria.
Bacteria seem to be thought of as “simple” compared to many-celled organisms, but certain motorized bacteria (such as E. coli or Spirilla) reveal immense engineering complexity.
These motorized bacteria are hardly “simple”. The bacterium swims about with a whip-like cord called a flagellum (plural flagella), driven by a fantastic motor embedded in the outer shell. The flagellar motor is powered by proton flow, and closely resembles microscopic electric motors, powered by electron flow. The motor generates waves in the cord, which drive the germ forward.
A bacterial flagellar motor has the amazing quality of combining speed with efficiency. These extremely efficient motors can quickly stop, start, change speeds, and reach a top speed of about 100,000 rpm (revolutions per minute)!1,2 The cell is propelled up to 15 body-lengths per second at top speed.3 If this could be scaled up, it would be like a person of height 1.8 m (6 ft) swimming at 100 km/h (60 mph).
It is also very versatile, because it has forward and reverse gears, enabling the germ to reverse direction within a quarter of a turn.
Most man-made electric motors are up to 75–95% efficient at larger sizes, but lose efficiency as they get smaller.4 The bacterial motor is almost 100% efficient at cruising speed.5 The bacterium uses only 2% of its total energy for swimming.6
Biological flagellum motors are also superior in their minute size. The smallest man-made electric motor weighs 0.37 grams and is the size of a housefly,7 but bacterial motors weigh almost nothing. To view them you need an electron microscope, because they are 25 nanometres (one millionth of an inch) in diameter.
Eight million of them would fit in the cross-sectional area of an average human hair.8 Scaling a regular electric motor to this size would bog it down with friction, because water tends to get “stickier” as things are smaller. But it does not cause any problems for the flagellar motor.
There are no motors of any type that are as rapid, efficient, and small as flagellar motors in bacteria. Could such a motor that far exceeds man’s inventions be the result of a cosmic accident billions of years ago? Every example of man-made electric motors proves to be primitively clumsy compared to the superior complexity and efficiency of the flagellum motor. The reasonable solution is that motorized bacteria had an all-wise designer, Jesus Christ our Creator (John 1:3; Hebrews 1:2).
“For the invisible things of him from the creation
of the world are clearly seen, being understood by the things that are made,
even his eternal power and Godhead; so that they are without excuse” (
Scientific American tried to explain this amazing miniature motor by evolution, by claiming that the parts were “co-opted” from other functions:
“The sophisticated components of this flagellum all have precedents elsewhere in nature …
“In fact, the entire flagellum assembly is extremely similar to an organelle that Yersinia pestis, the bubonic plague bacterium, uses to inject toxins into cells. …
“The key is that the flagellum’s component structures … can serve multiple functions that would have helped favor their evolution.”1
Scientific American’s argument is like claiming that if the components of an electric motor already exist in an electrical shop, they could assemble by themselves into a working motor. However, the right organization is just as important as the right components.
Dr Scott Minnich of the University of Idaho, a world expert on the flagellar motor, disagrees with Scientific American. He says that his belief that this motor has been intelligently designed has given him many research insights. Minnich points out that the very process of assembly in the right sequence requires other regulatory machines.2 He also points out that only about 10 of the 40 components can possibly be explained by co-option, but the other 30 are brand new.
Finally, Dr Minnich’s research shows that the flagellum won’t form above 37°C; instead, some secretory organelles form from the same set of genes. But this secretory apparatus, as well as the plague bacterium’s drilling apparatus, are a degeneration from the flagellum. Minnich says that although it is more complex, the motor came first, so it couldn’t have been derived from them.3
Answers in Genesis is an apologetics ministry, dedicated to helping Christians defend their faith and proclaim the gospel of Jesus Christ effectively. We focus on providing answers to questions about the Bible—particularly the book of Genesis—regarding key issues such as creation, evolution, science, and the age of the earth.