How Giraffe Necks Stretched to New Heights

By Nathaniel Scharping | May 17, 2016 3:07 pm
shutterstock_250785079

(Credit: Pearl Media/Shutterstock)

When you picture giraffes, there’s one detail you certainly won’t overlook: their necks. Their serpentine necks account for almost half of their height, and a significant amount of their fame.

In a new study that sheds some light on just how giraffe necks stretched to such heights, researchers from Pennsylvania State University and the Nelson Mandela African Institution of Science and Technology have sequenced the giraffe genome, as well as the genome of its closest relative, the okapi, for the first time. The analysis highlights 70 genes that show signs of adaptions unique to giraffes, which researchers say play a key role in giving giraffes a chin up on other animals.  

Unique Neck

Unlike some species of long-necked birds, giraffes didn’t grow their necks by adding vertebrae to their cervical spine, they just stretched out the seven vertebrae they already had. So, giraffes necks must undergo a period of rapid growth while they are young.

And it takes some complicated natural engineering to support such an outlandish feature. In addition to the obvious muscular and skeletal concerns, giraffes have also evolved an oversized left ventricle and reinforced circulatory system to handle the stress of pumping blood almost ten feet straight up to their brains. They also have specialized blood vessels in their heads and necks that regulate blood flow while bending down to drink, preventing sudden changes in blood pressure every time they take a sip of water.

shutterstock_80823655

(Credit: belizar/Shutterstock)

The Long and Short of It

To figure out just how giraffe necks stretched, researchers from the Giraffe Genome Project compared the giraffe genome to that of the okapi, their nearest relative and the only other surviving member of the family Giraffidae. Okapi look like a cross between a cow and a zebra, although their skeleton is quite similar to that of a giraffe — minus one very prominent feature, of course. The researchers say that giraffes and okapi split around 11.5 million year ago, after which giraffes underwent a tremendous growth spurt.

okapi

The okapi and the giraffe diverged from a common ancestor only 11-to-12 million years ago. (Credit: Raul654)

Of the 70 genes that the researchers say show signs of adaptions between giraffes and okapi, around half likely play a role coding proteins that regulate skeletal, muscular and nervous system development — all important for producing their notable necks. For giraffes’ necks to grow so long, two crucial things need to happen: First, the genes that tell the neck when to stop growing needed to be turned off; second, genes that promote growth need to be upregulated.

They singled out one gene in particular, FGFRL1, as playing a key role in promoting neck growth. The gene possesses adaptions unique to giraffes, and is responsible for regulating embryo development, particularly the skeletal and cardiovascular systems. Also of importance are four so-called “homeobox” genes that come into play during the giraffes’ development from an embryo into adolescence. These four genes also have unique adaptions that the researchers think instigate rapid growth in giraffes’ cervical vertebrae. They published their work Tuesday in Nature Communications.

Painting a Clearer Picture

Exactly how many of these genes influence giraffe development is unclear — their necks are likely the result of complex interactions between many genes. But by comparing giraffes to a close relative and identifying genes that show differences between species, researchers can build a pretty good idea of which genes are responsible for making them look so different.

As a next step, the researchers plan to inject the FGFRL1 gene into mice using CRISPR-CAS9 technology to see how it affects growth. While they caution that creating long-necked mice is unlikely, they hope to observe changes in the development of the spine that could clue them in to how giraffe necks grow.

CATEGORIZED UNDER: Living World
MORE ABOUT: animals, evolution, genetics
ADVERTISEMENT
  • OWilson

    No discussion here of natural selection, but it is clear they have filled a niche at the top of the evolutionary tree!

  • ZappaSaid88

    No!! God stepped on it’s toes and pulled its head. He had help from his other son Jesus Chiro founder of Chiropractorism.

    • Carmine007

      GROANNNNNNNNNNN…. Don’t give up your day job, yet.
      lolololololololol
      ^5s
      Best one I’ve seen today.

    • Rich

      Zappa, you funny dude, the design features of special valves in the arteries and the web of veins around the brain mentioned in the article clearly demonstrate that the giraffe was created as a giraffe. We cannot even begin to imagine the amount of new information that would have had to be encoded into the DNA to bring about such design changes. I will hand it to you that “God stepped on it’s toes and pulled its head…” IS far more scientific than myth of transmorphic Darwinism which was disproved scientifically by Louis Pasteur back in 1863. With what we know from the advancements in the Information sciences, in chemistry, biology, genetics and physics, it is a mystery that anyone can say with a straight face they don’t believe in a Creator. Evolution is not only not science, it is anti-science, it violates all the laws of science. Several years ago this very publication said something to the effect, “everybody knows evolution is true; the problem is there is no evidence that it is true.” And to that I say, “Amen!” Eternity is too long to be wrong, my friend.

  • T. Jefferson

    * I can’t stop laughing…. You people must think we are all idiots… Please tell us that it took a Trillion years to make that happen… then back it up with evidence and show us how this process can be duplicated….’Only the FOOL has said in his heart….there is no God’.

    • Jason Dries

      No, I think the fool has just spoken here. Thanks for the laugh.

    • AncienReggie

      Do you even have a clue how long a trillion years would be?

  • Rich

    I have to agree with T. The article talks about “complicated engineering” and “complex interactions” which are always the result of an intelligent designer. Zappa scoffs at such logic while eagerly swallowing that billions of damaged DNA birth defects morphed an okapi into a giraffe 11.5 million years ago, and trillions upon trillions of birth defects turned a rock into an okapi starting billions of years ago. OWilson mentions Natural Selection, which, albeit imperfectly, keeps most birth defects from being passed on to future generations (though an estimated 100 new birth disorders are added to the mutation load each generation), keeping the copies as close to the original creation with all its genetic variety and variability as possible. Evolution is not only not science, it violates every known law of science. It only works in science fiction. This article reminds me of a TV science show about how marvelously our brains are designed and constructed and the narrator said with a straight faith, “It appears that evolution was so smart, it designed us with the ability to forget trivia.” If science proves anything it proves there is a Creator (our founding fathers called it a self-evident Truth).

    • cgosling

      I often hear from Christians that there had to be a designer. They like to refer to a building and claim without a designer it could not have been built. In actuality, it took many designers and several architectural companies to have built it. In addition millions of other designers, inventors, and workers of the past as well as in the present lent their skills to this building including plumbers, electricians, and many other specialists. Therefore, I can only presume that there are many Gods, not just one who creates life.
      Another gripe have is the watch fairy tale. You find a watch that could not have created or assembled itself, and from that you assume it had to have a creator. What bunk! Time keeping inventions of the past are many. Eventually, all these inventions led to a more accurate time piece, an atomic clock. To claim that our current methods of telling time are due to the talent of one creator is ridiculous. Again, there were literally many thousands of inventors and technicians that can be credited for the design and construction of that watch you found. Once again logic tells me that no one entity or God designed a watch. Instead there were uncountable contributions from an unknown number of humans. Religious debaters have no reply to simple logic and science.

      • Rich

        Your illogical argument is self-refuting. As you point out, in summary, everything that IS requires a beginning and a CAUSAL AGENT; but that beginning is not many gods evolved from the cosmos as the pagans of Babylon, Rome, Greece, and accent alien theorists propose, but one ever-existing, all-knowing, all-powerful, super-genius designer and builder. Anything less, of course, would not be God. Even the least religious of our founding fathers, Thomas Payne, lectured the French Enlightenment with (I paraphrase) “how foolish to teach gravity and talk only of Newton its discoverer, and not teach gravity’s Creator.”

        • cgosling

          Rich , words come easy to you, but not logic. Review again what I logically claimed. We know one designer did not invent and construct a watch. It took many inventors and skills including metallurgy, physics, mathematics and mechanics to mention just a few specialties. You cannot deny this logical statement. It has nothing to do with religion. One inventor did not invent the timepiece on your wrist. It took many. Agreed? If it is logical that if it took many designers to design a watch, then it took many designers to create life. This comparison is yours not mine. I am simply pointing out your illogic. By the way, I do not believe in many gods as you suggest. I just believe in one less than you.

          T. Jefferson, you quote ‘Only the fool has said in his/her heart… There is no God’ without any references except some Bronze Age nonsense which has been copied and edited hundreds of times. It is beyond logic to accept bible fairy tales as truth. If your only claim to logic is because it was written in the bible, you are truly gullible. As you must admit, the bible is filled with contradictions and atrocities. Many books have been researched and written on the subjects. The sciences of archaeology and biology have disproved much of what is written in the bible. Our friend Thomas Paine thoroughly disputed the accuracy of biblical text in his Age of Reason by pointing out that if one finds so many inconsistencies in it, then how can one believe anything with assurance? The founding fathers were not Christian in your sense of the word, they were deists at best, and spoke out strongly against mixing supernatural beliefs with government.

          • OWilson

            You fall into the usual atheistic logical trap.

            In our science method we infer there is a cause for every observed effect. We seek to define that cause and obtain consistent predictability.

            To imagine our complete universe, with it’s strict laws of motion, speed limits and atomic size limits, self awareness and human emotion suddenly springing from nothing, violates the scientific principal.

            That is REALLY asking one to believe in miracles :)

            It is much easier to believe that an enterprising.caterer was able to feed a whole bunch of people with a few fish on the shore of the Sea of Galilee, and perhaps perform a few other “magic” tricks during his lifetime.

          • cgosling

            Dear OWilson, I wonder what it was that convinced you to believe in a specific Hebrew/Babylonian deity. Was it by the influence of birth and family or was it your choice after you learned about science? I find it illogical for anyone to believe in an all powerful creator/designer that always existed and yet be unable to accept that matter and energy always existed. Science has no evidence of a deity or deities, but scientific inquiry has plenty of evidence of energy and matter. Are you not taking a huge jump in logic to believe that your deity needed no creator. If everything needs a creator, why do you believe that your deity does not? How did you ever come to that conclusion? Just wondering what makes people tick. Thanks.

          • OWilson

            Well, I am an atheist, so your self serving strawman arguments don’t impress me much.

            The only arrogance and certitude that exceeds organized religion, is that spouted by “settled science” advocates, who don’t even understand the basic constituents of the 90% or so of the universe they live in. :)

          • cgosling

            OWilson, Glad to hear you are an atheist. As you know just being an atheist does not make a person good. As far as “settled science”, very few good scientists believe in settled science. In fact, settled science is an oxymoron, no such thing. Scientists, like atheists and agnostics, are always open to correction and change. I think we agree on that. As far as assuming everything has a cause, it is a huge assumption. We don’t know if everything has a cause. I ask my religious friends who use that argument, did their God have a cause or did he always exist like our univers, which actually did not always exist. It may have been created by other matter and energy sometime in the past. I can’t claim I can answer that question with the certainty of those who claim God always existed. My religious friends stop their investigation of the universe at their concept of God. Why think any further? It was good exchanging thoughts with you. Thanks

          • Rich

            The illogic of your argument is found in that it requires the continual input of new design and intellect which evolution cannot provide. On the other hand, the law of entropy proves that at some point in the past the omniscient and omnipotent creator brought everything into being in the highest state of perfect order, but now it is running down. The only thing you argument PROVES is that all design requires and intelligent designer. Natural Selection does not create new order, its function is to keep each copy as close to the original as possible. You are as ill-informed on history as on science. Not one of our founding fathers was a deist. Payne was not a Christian, but he was a theist and a creationist. The rest, including Jefferson and Franklin, claimed to be Christian. And not only has archaeology NOT disproved the Bible, because of its historical and geographical accuracy it has been referred to as the Archaeologist’s Handbook. The Bible is full of thousands of tribal names, names of rulers and kings, nations, rivers, towns, cities, mountains, etc. and every archaeological discovery only adds to the mounting evidence that the Bible is the most accurate history of the ancient world. I would encourage you to read “There IS a God!” by Sir Anthony Flew, the most famous atheist of the 20th Century, or the Case for Creation by Lee Strobel, or Evidence That Demands a Verdict by Josh McDowell, or just read the Bible itself. I will be praying for you that you will come to a knowledge of the Truth before that day in which you will stand before your Creator. He is very likely to ask you about this conversation.

          • cgosling

            Rich You are repeating the same old religious arguments I have heard too many times. For your information, evolution is in action ALL the time and It does not require any kind of designer. You do not understand evolution. Like Darwin, I do not claim to know how things began. and neither do you in spite of your faith in a book written in The Bronze Age by unknown authors and scribes. But, I do understand how evolution works and judging by your statements, you don’t. You need to read contrary views to yours written by evolutionary scientists. The old arguments about creation have been disproven over and over, but you obviously refuse to accept them. If you are happy living in a superstitious world, and deny simple science, good for you. Good luck.

          • Rich

            I have already truthfully answered your ignorant generalizations about the Bible. Unless you believe that God created you and loved you so much that he sent Jesus to die your deserved death, and you repent of your rebellion against God, and ask him to forgive you and give you eternal life, you will spend an eternity separated from God in hell. God has given you free will and he loves you too much to violate your choice, but I encourage you to ask God to reveal himself to you, and I encourage you to read the Bible (his love letter to you).

            As far as science is concerned, maybe, our definitions of ‘evolution’ differ. When you say “evolution is in action ALL the time,” to what are you referring? Everybody knows there is change from generation to generation within kind…that’s adaptation: simply making use of the vast genetic diversity God encoded in the DNA at creation. NEVER do we see anything remotely approaching change of one kind of animal to another, which would require massive input of new coded DNA information; that NEVER happens. All mutations are LOSS of information and Natural Selection works to weed these ‘birth defects’ out. Only science FICTION makes a superhero of a mutant. Of course, you and Darwin know where everything came from, you just won’t admit it, like Dr Wald, head of Harvard’s Science Department for many years, who said, “When it comes to the origin of life there are only two possibilities: spontaneous generation and special creation. Spontaneous generation was disproved more than a hundred years ago! That leaves us only with special creation. But we refuse to accept that based on philosophical grounds. THEREFORE, WE ARE LEFT WITH THE UNENVIABLE POSITION OF HAVING TO BELIEVE THE IMPOSSIBLE!”

  • Courtney Schumacher

    Nate, you don’t say HOW Giraffes necks stretched; you only said THAT they did. I wanted to see someone else talking about a mixture of Lamarkianism and Darwinism. Animals of an okapi’s size NEEDED to get more food from higher tree branches, and the taller ones not only could reach that and pass their ‘tall’ genes on, but they had stretched, so changed their own DNA. A guy keeps making new sperm for life, so he could pass that change on. Eggs are already stuck with the old genes.

    • OWilson

      The presumption is that natural selection stretched their necks to give them an advantage in the tree top browsing department.

      It is just as valid to suggest that their increased height gave them a better advantage to see and smell trouble.

      For the same reason my SUV is safer than a low hanging sports car on a highway :)

      • T. Jefferson

        Did your SUV have a designer or did it just appear? ….

        • OWilson

          Maybe Henry Ford had a little to do with it, but I like to think of it as my “chariot of the gods” :)

          • T. Jefferson

            *Thank you…. Your SUV had a designer and so did the Giraffe have a Designer…..

          • OWilson

            Who designed the designer?

          • T. Jefferson

            *He ALWAYS was and Always will be…

          • Courtney Schumacher

            That is a standard ‘out’ to that question. If God had ALWAYS been, then He would have NO sense of time passing. Just as one day to him could be a million years to us, so could one day to him be nanosecond to us.
            And before he’d created the universe, he’d have had no little balls to show time passing.

          • T. Jefferson

            * It is amusing to see the creature trying to understand the Creator…”Does the clay say to the Potter ‘why did you make me this way’?

          • Courtney Schumacher

            TJ, you are ONLY using standard evasive techniques; you are NOT arguing. You have nothing original to say, so you are not worth it.

          • T. Jefferson

            *I’m sorry Courtney…. I was just quoting the One who Created the Giraffe….

          • OWilson

            He?

      • Courtney Schumacher

        OW, I had just wanted to see some scientific evidence so I’d know what to pass on to doubters. _I_ know they evolved that way, and how (some Darwin, some Lamark), but just _I_ can’t convince others who are set in their ways.

  • http://www.RNA-mediated.com jvkohl

    Journal article excerpt: “Giraffe FGFRL1 contains seven amino acid substitutions that are unique at fixed sites in other mammals…”

    In all vertebrates and invertebrates, fixation of energy-dependent RNA-mediated amino acid substitutions occurs in the context of the physiology of reproduction. The substitutions link energy-dependent changes in base pairs from hydrogen-atom transfer in solutions like seawater and blood to all cell type differentiation.

    Amino acid substitutions link metabolic networks to genetic networks via the innate immune system and supercoiled DNA, which protects the organized genomes all living genera from the virus-driven energy theft that links mutations to all pathology.

    For God’s sake, if you do not known how all energy-dependent cell type differentiation occurs in all individuals of all species search Google for “RNA mediated” or PubMed for “microRNA.” More than 50,000 indexed publications on PubMed link what is known about energy-dependent microRNA flanking sequences to the RNA-mediated amino acid substitutions that are the link between the National Microbiome Initiative and the Precision Medicine Initiative.

  • wangweilin

    70 genes properly sequenced. Not a small number. 2^70=1.18E21. That’s just to get the proper combination not including timing and all the associated metabolic processes. While the research shows the observed differences between the okapi and giraffe genome the article doesn’t say how as implied by the title.

  • khalid sideek

    I wonder why other herbivores did not notice what the genius Giraffe did and tried to elongate their necks?!
    Besides, since they have such ability, why didn’t they try to reinforced their necks by some hard bones so the Predators can not kill them by biting those necks؟!

    Haha.. only tiny questions from an idiot tiny neck creationist

    I remember when I was a fish, I told my fellows to evolve directly from the sky not from the land, but they refused.. See now, it took too long to be a human!

  • Kermit Blackwood

    Due to the frequency of flooding and periodic need to escape predation by taking to the water, Okapi have retained what is assumedly an ancestral condition giraffes lack. This is capacity to swim efficiently in deep rivers from an early age.
    The next closest living relatives of giraffes and okapi, the pronghorns, are endemic to North America and are known for their great speed and endurance as runners.

NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

D-brief

Briefing you on the must-know news and trending topics in science and technology today.
ADVERTISEMENT

See More

ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Collapse bottom bar
+