Tag: metabolism

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Endothermic or Ectothermic – What’s the Difference?

Endothermic or Ectothermic – What’s the Difference?

You are an endothermic mammal. That means your body’s metabolic rate controls your internal body temperature. We describe that condition by saying you are “warm-blooded.” Many life forms on our planet are “cold-blooded” (ectothermic) because the environment controls their internal body temperature. The limitation of being cold-blooded is that it requires warm environmental temperatures. Ectothermic life forms can’t survive in polar areas. Endothermic life can survive almost anywhere.

During the time of the dinosaurs, the planet was very hot. That means biological systems, including plants, grew quickly. Those conditions were part of God’s preparation of resources that humans would need, including oil, coal, topsoil, and oxygen. However, the geologic record shows a point in Earth’s history when the climate radically changed. 

As the entire planet cooled, areas at or near the poles became too cold for cold-blooded life to exist. Studies of bone growth rates and oxygen isotopes in ancient bones indicate a rapid change. This change would not be a problem for warm-blooded animals but would reduce the number, size, and activity of cold-blooded life forms.

The challenge would be to design living creatures that can translate food into enough internal heat to survive in a cold environment. Science News reported on studies of the inner ears of reptiles and mammals. In warm-blooded animals, the inner ear fluid is less viscous, requiring that the ear canals become smaller. As a result, fossils show a sharp change in inner ear morphology at the time when Earth’s climate became colder. 

Many other changes were required for life to go from ectothermic to endothermic. However, the inner ear structure is preserved in the fossils, making it useful for scientists to study the history of life on Earth. The complexity of endothermy reminds us again of the words of Psalms 139:14, “I will praise you, for I am fearfully and wonderfully made: marvelous are your works.” In our time of changing climate, the design of life continues to show the wisdom involved in life’s creation. 

— John N. Clayton © 2022

Reference: Science News August 27, 2022, page 9, and Nature.com

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Arctic Ground Squirrels Hibernate

Arctic Ground Squirrels Hibernate

Squirrels in Arctic areas seem to have a hibernation technique which could be described as suspended animation. Arctic ground squirrels (Urocitellus purryii) go into a state of deep torpor breathing once a minute with a heart rate of five beats per minute. Every two to three weeks, the squirrels revive for 12 to 24 hours, but they don’t eat, drink, or eliminate during that time.

Researchers from the University of Alaska, Fairbanks, have found that hibernating Arctic ground squirrels have skeletal muscle breakdown, releasing nitrogen to compensate for lack of food. Even though this is happening, the squirrel’s total muscle mass doesn’t change. It appears that they have protein stored up to handle their needs, but scientists are trying to understand where and how that protein is made available. This is another designed characteristic that allows life to exist in the Arctic.

Realize that there are unique problems in an ecosystem that is shut down for eight months. The design of larger animals allows them to migrate, and caribou herds go great distances to survive the Arctic winter. The migration of salmon into Arctic waters is another provision for animal survival. The salmon become food for Arctic animals, and their bodies become fertilizer so plants can grow in an area with virtually no soil.

Smaller animals have a big problem because they can’t migrate, and their plant-based food sources have a very short growing season. It appears that Arctic ground squirrels are a vital link in maintaining the balance of food and plant growth. The squirrels bury seeds so new plants can grow, and they provide a nutrient source for predators like wolves and wolverines. The complexity of how they do this has led to a whole new area of biology with its own magazine–Nature Metabolism.

Scientists are researching the Arctic ground squirrels’ metabolism to understand how this complex system works. Whatever the biochemistry involved, it is highly complex and strongly supports the belief that God designed life forms to survive even in a cold environment.

— John N. Clayton © 2021

Reference: Nature Metabolism December 7, 2020 and Science News for January 30, 2021, page 10.

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DNA Barcodes Support Biblical Record

DNA Barcodes Support Biblical Record
Nearly every day the newspaper has an article that announces some new research on DNA. One of the recent applications of DNA research is to classify living things. Classification is an old issue, going back to Adam and Eve. In Genesis 2:19-20 God brought all kinds of living organisms before Adam so that he could name them. In 1 Kings 4:33 Solomon wrestled with the issue as well. Our current system of naming living things was brought into existence by Carl Linnaeus in the 1700s, but it is gradually being replaced by what is called DNA barcodes.

You can compare DNA barcodes to the barcodes we see when we shop for merchandise. Instead of bars, DNA barcodes are a string of DNA nucleotides. In 2003 scientists began to identify species by these nucleotides. Mitochondria are rod-shaped organelles that can be considered the power generators of the cell. They convert oxygen and nutrients into adenosine triphosphate (ATP), the chemical energy that powers the cell’s metabolic activities. There is one gene named cytochrome c oxidase subunit 1 (COX1) which is found in mitochondria. It is passed only from mother to offspring. The mixing of traits from the father and mother does not happen in this mitochondria, so the DNA nucleotides in mitochondria make it ideal to use in identifying species.

Studies by M.Y. Stoeckle and D.S. Thaler have involved analyzing the DNA barcodes from five million individual organisms which represent 100,000 different species. What they found was that barcode variations within a species vary by small amounts, and there are huge gaps between the species. What that means historically is that each species is essentially an island not connected to other species. If all species came from a common ancestor, you would not see this, but you would see a river from island to island.

The biblical record is very consistent in identifying the groupings of living things. In our materials, we have referred to these “islands” as being “trees in the forest of life.” First Corinthians 15:39 identifies these “islands” or “trees” in this way: “There is one kind of flesh of men, another flesh of beasts (mammals), another flesh of birds and another flesh of fish.” This same grouping is used consistently in the Bible with Genesis 1 & 2 in describing the creation of life, Genesis 7:14 describing what Noah took on the Ark, and 1 Kings 4:33.

There are many more trees or islands than the Bible describes, and they contain living things that may vary enormously. A major debate in science is whether the dinosaurs were birds or reptiles. DNA barcodes may answer that question, but the implications for the biblical record are not significant. The single “tree of evolution” which has been popular for a very long time does not fit the DNA bar code evidence, but the biblical system does. New research is leading to new understandings both scientifically and biblically. It is an exciting time to be alive and to learn from new scientific tools how accurate the biblical record is and how wise God has been in His creation techniques.
–John N. Clayton © 2019

For further information, go to this website: https://micro.magnet.fsu.edu/cells/mitochondria/mitochondria.html