How Human Egg Cells Last Decades

The fact that human eggs last for over
40 years baffles scientists. New research
has found out how they do it

by Jerry Bergman, PhD

Introduction

I often hear from both creationary and evolutionary biologists that learning about the wonders of the incredible design of all life was a major attraction for them to study biology. The main difference is, creationists believe the design was due to the genius of an intelligent designer, whereas evolutionists believe the design was due to mindless natural processes. Evolution works by damage to the genome called mutations which provides genetic variety that is culled by natural selection. In time, supposedly, the assumed progress adds up. After long periods of time it has produced all life forms, including humans.

One area of new research is on why most human body cells have a short lifespan, except for a women’s egg cells. Anatomists call these cells ova (singular ovum). An egg before maturation is called an oocyte.

How Can a Woman’s Eggs Last For 40 Years?

A woman is born with all the ova she will ever have in her lifetime. Even after four decades in the woman’s body, most of these ova are still viable.[1] In contrast, new male gametes called sperm have to be constantly created in adult males. Male gametes from ejaculated sperm remain viable for only a few days even within the female reproductive tract. Fertilization is possible as long as the sperm cells remain alive which is usually, at the most, for five days. Although sperm can be preserved for decades when frozen, at room temperature only a few days of viability is normal. This leads to a question that has puzzled anatomists: how are ova able to remain viable for 40 long years when sperm cells are viable for only about five days?

The Process of Cell Replacement

Most of our cells are constantly dividing, growing, and dying. This process is so extensive that humans are said to have a new body after seven years. The human body replaces many cells every seven to ten years. There are exceptions; the heart, eyes, and the neurons in our cerebral cortex, are all structures which largely remain intact from birth to death. Most routine cell replacements occur in the skin, bones, liver, stomach, and intestines. Over 330 billion cells (about 1 percent of all our body’s cells), are replaced daily. Other cells, such as the gut cells, renew within close to a week.[2] This enormous difference in longevity was the subject of the research reviewed in a paper published by Szalinski et al. in PNAS on October 23, 2024.

Although most of the body’s proteins break down within hours or days, some protein types, appropriately named long-lived proteins, can last for months or even years.[3] Long-lived protein is the term given to proteins that are turned over slowly or not at all. Examples include elastin and collagen, and protein within specialized nondividing cells, such as the eye lens crystalline proteins.  The label refers only to the longevity of the protein, not its specific design, and several factors are involved in the proteins longevity.[i]  In other words, their longevity is due to many factors both internal and external to the protein, a topic researchers are just beginning to understand.

[i] Truscott, R. (Editor) Long-Lived Cells and Long-Lived Proteins in the Human Body. New York: Wiley.

Aging is partly the result of the imperfect replacement of our body’s proteins. In contrast, women are born with all the eggs they’ll ever have, and even after many years in the body, these eggs can create new life if fertilized. The new research was an attempt to answer the question of how and why these ova survive so long.

The Research

The research methodology employed by Szalinski et al., used pregnant mice that were fed chow to which was added

a modified version of the amino acid lysine. This version had a heavy form of carbon that would be incorporated into any proteins made in female embryos. By feeding pups only normal lysine after birth, the team could figure out which proteins in grown-up mice were made before birth and which after. Looking at thousands of oocytes, the researchers found that about 10% of the proteins made in oocytes before birth were still present when the mice were at their peak fertility, which is 8 weeks old.[4]

In order to better understand

protein turnover, the researchers also tracked the proteins in mouse oocytes up to 65 weeks—well past the mouse equivalent of perimenopause. The team calculated that about 10% of the types of proteins present during that time had an unusually long half-life—the time it took for half the proteins present to fully disassemble into their amino acid building blocks—of over 100 days. Only 1% of proteins in the mouse brains had similar staying power; 352 distinct proteins lasted nearly the entire lifespan of the mouse.

This research documented that two types of protein exist, long-lived protein and non-long-lived protein. This explains why, even after four decades in the woman’s body, these eggs can create new life if fertilized. Furthermore, both repair proteins and proteins that function as antioxidants, were also more common in long-lived cells.

Why This Challenges Darwinism

This finding has added another layer to the complexity of life. The result was confirmation that the animal body is more complex than previously thought. This adds another layer of complexity that must exist for the next generation to exist. Otherwise, if the correct type of protein is not present in certain cells during development, natural selection would come to a grinding halt in one generation.

The results of this and other research have determined that certain types of long-lived proteins were found in oocytes that were not present in most other cell types. This included finding long-lived proteins in mitochondria that were critical for cell energy production, as well as proteins that help the cell maintain its structure. Not only were different proteins present in long-lived cells, but long-lived proteins were also found to be much more common in chaperone cells than in other cells. Chaperone proteins, as the word chaperone implies, assist other proteins to fold properly both during or after protein synthesis. They also help proteins to refold after partial denaturation and even participate in protein unfolding, and protein assembly and disassembly.

Use of long-lived proteins by the body have another benefit, namely they reduce the cell’s energy demands, consequently reducing the number of by-products called reactive oxygen species from energy production that cause cell damage. Cells require a system to dispose of both damaged proteins and even some long-lived proteins. This housecleaning is especially important for to mature oocytes in preparing to produce a healthy embryo. Long-Lived protein also resists denaturation that renders the cell nonfunctional.[5] In short, long-lived cells were specially designed to be long-lived for very important reasons.

Summary

We now have two divisions of proteins—long-lived and non-long-lived—each playing a critical role in life. Constant maintenance and repair of egg proteins explains why a woman’s ova can remain viable after 40 years. It also explains why a decrease in the number of long-lived proteins caused a decline in fertility.  If these specially designed proteins did not exist, many life-forms also could not exist.

This finding illustrates the fact that specified complexity of life increases as research progresses. Complexity per se does not support intelligent design. The minerals contained in granite (including feldspar, quartz, mica, and amphibole) are complex, as is a string of 100 random letters. It is not mere complexity, but specified complexity that matters in evaluating design. Specified complexity takes the form of functional information and it is this complexity that increases as biological research progresses.

 

References

[1] Bomba-Warczak, E.K., et al., Exceptional longevity of mammalian ovarian and oocyte macromolecules throughout the reproductive lifespan, eLife 13:RP93172, 26 September 2024.

[2] Opfer, C., and Trouter, A., Does your body really replace itself every seven years?, https://science.howstuffworks.com/life/cellular-microscopic/cell.htm, 2022.

[3] Szalinski, C., Protein research may hint at how human eggs survive for decades, PNAS 121(44):e2419809121, https://doi.org/10.1073/pnas.24198091, 23 October 2024.

[4] Szalinski, 2024.

[5] Wankhede, N.L., et al., Involvement of molecular chaperone in protein-misfolding brain diseases, Biomedicine & Pharmacotherapy 147:112647, March 2022.

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Dr. Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology for over 40 years at several colleges and universities including Bowling Green State University, Medical College of Ohio where he was a research associate in experimental pathology, and The University of Toledo. He is a graduate of the Medical College of Ohio, Wayne State University in Detroit, the University of Toledo, and Bowling Green State University. He has over 1,900 publications in 14 languages and 40 books and monographs. His books and textbooks that include chapters that he authored are in over 1,800 college libraries in 27 countries. So far over 80,000 copies of the 60 books and monographs that he has authored or co-authored are in print. For more articles by Dr Bergman, see his Author Profile.