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Creation 40(4):24–26, October 2018

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An eggcellent design

Eggshell nanostructure shows purposeful construction



The question of whether the chicken or the egg came first has been asked for thousands of years.1 However, any reader of Genesis will readily see that the answer is the chicken (or more accurately the landfowl kind), created on Day 5, which then laid an egg.

Renowned evolutionist David Attenborough, who denies any role for God in the egg’s design, has nonetheless described eggs as “miracles of nature” and the egg as “an excellent life support system”.2 The eggshell not only protects the chick developing inside, it acts as a semipermeable membrane that lets air and moisture pass through about 7,000 pores in a controlled fashion. This allows the chick inside to breathe, while protecting it from drying out due to a net loss of water.3

Now details of the first ever nanostructure examination of fully formed eggshells of the domestic chicken, Gallus gallus domesticus, have been published showing superb design in their formation, function and dissolution.4

Researchers from McGill University were able to accurately cut thin slices of the eggshell and “found that a factor determining shell strength is the presence of nanostructured mineral associated with osteopontin, an eggshell protein.”5 Osteopontin was discovered to be a binding agent, helping to form the superstructure of the eggshell, guiding the framework and controlling the arrangement of the calcium carbonate in the shell. In the outer layer of the eggshell, there were high levels of osteopontin, meaning that the structure is more closely and densely formed. This keeps the hard shell protective on the outside while the chick is getting ready to hatch. However, in the inner layer of the eggshell, there were lower levels of osteopontin. This means the nanostructure was larger and more loosely arranged, which made the calcium carbonate more accessible and thus allowed the inner layers to dissolve more readily.

Eggshells and tiny teeth

by Jenny Arms

Uberprutser CC BY-SA 3.0 via Wikipediachicken

Adding to these marvels of the eggshell’s purposeful design is the ingenious tool the tiny chick needs to break out to freedom—the ‘egg tooth’. This is a horny protrusion on the tip of its upper beak that starts to develop on day 7 of its gestation.

Some three days before hatching, the growing chick is finding it hard to get enough oxygen through the pores in the shell, so it uses its ‘toothed’ beak to slice a hole through the membrane into the air sac at the shell’s flatter end. This stored air gives it just enough extra oxygen to cope with the coming task of ‘breakout’.

At the right time, a muscle behind the chick’s neck begins spasming, encouraging it to ‘pip’ through the outer membrane and shell with its tiny ‘tooth’ tool. Thousands of times it chips the shell, rotating counter clockwise at its flatter end. This mammoth task requires hours of rest between bursts of activity. 

Finally, it happens! Fresh air. Success! With one huge kick, the chick is born—exhausted, wet and sticky. The ‘tooth’ gradually shrivels and falls away, culminating this unique and purposeful process, the information for which was programmed into its DNA all along. 

Jenny Arms is a retired Australian high school teacher (both secular and Christian) who lives in rural Victoria.

Two reasons for dissolution

Hatching is the climax of the egg’s experience, and the nanostructure of the egg demonstrates its wonderful dual-function design allowing the chick to hatch. The inner layer of the eggshell changes as the embryo grows and develops inside. The developing chick requires calcium to help form its bones, and it obtains this through dissolving the innermost layer of the eggshell.

In addition to helping the chick develop its bones, this dissolution also weakens the shell from inside, allowing the chick to be able to hatch when it comes to maturity, normally at 21 days.

Studying this process at the nanostructure level has made this design feature more fully understood. The research team highlighted that, “Such a process would allow retention of overall shell layer structure but with some thinning and compromised strength, a feature ultimately necessary for successful chick pipping to puncture/break the shell during hatching”.

Potential benefits

These latest nanostructure findings have been acclaimed as useful in the design and strengthening of bioinspired material, as well as helping to understand controlled solubility in biostructures. The finding will also be of particular importance to the agri-food industry as “eggshell quality is a major concern to the poultry industry since the percentage of broken or cracked (with possible microorganism invasion)6 eggshells can range from 13% to 20%.” One of the paper’s authors, Dr Marc McKee, explained that, “Understanding how mineral nanostructure contributes to shell strength will allow for selection of genetic traits in laying hens to produce consistently stronger eggs for enhanced food safety.”5

The evolutionary wink and nod

Despite the rather obvious design features of the chicken egg, and the potential applications of copying some of these, the researchers paid the usual homage to blind evolution. McKee said: “When you think about it, we should be making materials that are inspired by nature and by biology because, boy, it is really hard to beat hundreds of millions of years of evolution in perfecting something.”7 Yet the paper never even hinted at explaining how such a wonderful biomineralized life-supporting chamber could actually arise through hundreds of millions of years of a bit-by-bit evolutionary process. Like the waving of a magic wand, it’s as if just writing the words makes it so!

But there are many difficulties in this idea of the egg being perfected by selection of random changes over millions of years. Achieving this rather complicated balance of structural and mechanical properties needs to happen in different ways at different times of development. If the shell were not sufficiently strong outside, then it would not protect the chick. If it did not dissolve inside, then there would not be enough calcium for the bones to form, nor would the chick be able to break through and hatch. And if the thinning of the shell happened too soon, then it would compromise its protective function. How did the ancestors of today’s chickens reproduce for millions of years before that process was allegedly perfected to the point of ensuring the next generation of birds?

The research discussed here only scratches the surface of the many mechanisms involved in egg design and function, including other proteins, which are still poorly understood. The credit for this ‘eggcellent’ design8 does not belong to evolution, but rather to the One who is “worthy … to receive glory and honor and power, for you created all things, and by your will they existed and were created” (Revelation 4:11).

Photos: CC-BY-NC-4.0 Athanasiadou, D. et al., Ref. 4.osteopontin

To demonstrate how the osteopontin (OPN) affected nanostructure in synthetic calcium carbonate, calcite crystals were grown in its presence. Pictures A, B and C show no, low and high concentrations of osteopontin added to the synthetic calcium carbonate respectively. Notably, the measured nanostructure size from the synthetic calcite grown at the low osteopontin concentration was similar to the size found in the inner region of the eggshell, whereas the higher osteopontin concentration produced a nanostructure size similar to the outer part of the eggshell.

References and notes

  1. Fabry, M., Now you know: which came first, the chicken or the egg?, time.com, 21 September 2016. Return to text.
  2. Attenborough, D., Attenborough’s Wonder of Eggs, screened on BBC 2, 31 March 2018. Return to text.
  3. Science Buddies, Porous science: How does a developing chick breathe inside its egg shell? scientificamerican.com, 3 May 2012. Return to text.
  4. Athanasiadou, D., and 14 others, Nanostructure, osteopontin, and mechanical properties of calcitic avian eggshell, Science Advances 4(3) eaar3219, 2018 | doi: 10.1126/sciadv.aar3219. Return to text.
  5. McGill University, Cracking eggshell nanostructure: New discovery could have important implications for food safety, phys.org, 30 March 2018. Return to text.
  6. Chien, Y.C., and 3 others, Ultrastructural matrix-mineral relationships in avian eggshell, and effects of osteopontin on calcite growth in vitro, J. Structural Biology, 163(1):84–99, 2008 | doi: 10.1016/j.jsb.2008.04.008. Return to text.
  7. Davis, N., Scientists solve eggshell mystery of how chicks hatch, theguardian.com, 30 March 2018. Return to text.
  8. Catchpoole, D., What’s in an Egg? Unscrambling the mysteries, Creation 24(3):41–43, 2002; creation.com/egg. Return to text.

Helpful Resources

Discovery of Design
by Donald DeYoung & Derrik Hobbs
US $15.00
Soft Cover

Readers’ comments

Guillermo P.
Thank you! To God be the glory, who created such marvels for us to behold!
Lou M.
"The eggshell not only protects the chick developing inside, it acts as a semipermeable membrane that lets air and moisture pass through about 7,000 pores in a controlled fashion. This allows the chick inside to breathe, while protecting it from drying out due to a net loss of water."

Further to this and not mentioned, probably because it is not actually part of the eggshell but on its out side, is a coating which, while allowing air and moisture through, blocks infection from harming the developing chicken. If you have an egg which is dirty. even with faeces, which you wish to incubate, you can brush it off with a stiff brushing and the chick will hatch. If you wash the egg the protective coating is removed, and it is highly likely the chick will die in the egg from infection. Tell me how evolution provided this protection if you can!
Phil Robinson
The coating applied to the egg by the chicken just before it is laid is a protein outer covering known as the 'bloom'. This seals the egg preventing any pathogens from entering it. Yet another incredible protective design feature to keep the chick inside safe.
Greg F.
I appreciate Spoddy J. 's observation that because Evolutionary theory cannot provide an adequate explanation of something doesn't necessarily mean that Genesis does. I would however note that no popular proponent of Evolution theory [ Darwin, Hitchens, Sagan, Attenborough, Dawkins, Gould, Tyson ] ever shied away from very confident assertions that of course evolution is the only process that is even remotely conceivable for all that exists. After studying creationists' works for many years I personnally have concluded that their science is formidable and their arguements are satisfyingly cohesive. Note that empirical / operational science has shown to be reliable for our modern advancements and that MANY creationists have successfully worked and contributed within their fields. Be honest in your searching and examine the creationists arguements and observations. Also note that every acheological discovery that bears on the Bible has confirmed it.
Spoddy J.
If it can't be evolution then it must be God at work - ever hear of "We don't know?" What we do know is the verifiable findings of scientific research which tell us, in part, that we don't know very much, therefore the onus is on scientific research to expand our knowledge.
Phil Robinson
But we do know! God has very clearly told us in Genesis 1 that He created all birds on Day 5, which would have included the reproduction process for each bird kind created. To attribute the eggs magnificent construction to its designer is not only fitting, but the proper response. It is the 'verifiable findings of scientific research' highlighted by this research, and drawn out in the article above, that allows us to have a deeper glimpse into the wonder of Gods incredible creation. Any further scientific research into the egg will only serve to help acknowledge this further.
Douglas W.
So an atheist believes in miracles!
Geoff C. W.
And who told the chick that there was oxygen in the sac at the end of the egg, and who told it that it could break through the shell, and that that woud be a good idea because there was more oxygen out there? It wouldn't have even known that there was an 'out there' without some guidance from Someone!
Rodney P.
Thanks, Phil - an AWESOME article! I love your question: "How did the ancestors of today’s chickens reproduce for millions of years before that process was allegedly perfected to the point of ensuring the next generation of birds?" Darwin himself recognised that such questions can demolish his theory: “If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down. But I can find no such case.” Well, we keep finding such obvious cases over and over.

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