Wonder of Giraffes - Week 1 -Discussion

[Amy Darvill]

 

Is there anything more adorable then a baby animal?

 

Even if said baby animal is tall enough to play basketball...at birth?

 

Yep, when giraffes are born, they are already 6 feet tall, and they will grow up to be between 14 (most female giraffes) and 18 feet (most male giraffes) by the time they are 4 or 5 years old.  And we wonder why they earn the rank of the tallest land animals in the world. (Blue whales tend to be technically much longer but who's measuring?)

 

It's not just height that makes them so distinctive however, it's also the length of their necks that's unusual. Oddly enough, though you can kind of see if you've ever watched them move, it's not longer because they have more vertebres, it's longer because those vertebres are themselves longer. Each vertebra is one inch short of a whole foot, or 11 inches. That is massive. It's still only 7 vertebra, so you can kind of see that their necks can be a bit stiff.

 

There are many theories as to why they have such long necks. One of the most commonly accepted, pushed by Charles Darwin, is that it allowed them to beat the competition when it came to grazing. Most of the other grazing animals can only reach a maximum of little over 6 feet, but the giraffe can easily double that and more. It's also theorized that since bulls (male giraffes) do fight using their necks (called in a not romantic fashion here as 'necking') that basically the longer the neck, the more 'handsome' the bull. However, there are some trade offs for such traits, and currently, scientists are not a hundred percent sure that these are the right or only explanations. 

 

So what do you think? Feel free to report on another theory, give some pros and cons to these theories, or make up one of your own even, realistic or outlandish. 

 

Earn 25 Diamonds when you reply in here.  Please be sure to have at least 150 words in your reply to get full count of Diamonds.

 

You have until the end of January, HOL time, to earn your Diamonds.   

[Evie Figg]

While I do agree with Charles Darwin's theory as to why giraffes have such long, large necks, I do also want to elaborate on the grazing aspect of his theory. I do believe that giraffes necks are such grand in scale as to make it much easier for them to reach such tall, vast heights atop the trees, that other mammals cannot so easily reach. Giraffes happen to eat the leaves of Acacia trees, which can be a very tall feat for a smaller animal. Giraffes can easily just walk up to a tree, and reach out and munch onto the leaves located on the tallest branch! Only birds and other climbing animals would be able to meet them up there! These animals are such a unique creatures, as their necks make such a significant factor to their entire image and reputation. Although I do wish it were possible to own them, and ride atop our own giraffes like we do horses. The ride and view would be so spectacular!

[River Fenwick]

There are many theories about why a giraffe's neck has evolved to be as long as they are. It has stumped many scientific communities and giraffe lovers alike. Over the years, many assumptions and theories on this matter have been brought to the surface due to the discovery of fossils. For example, in China, there was a species that is said to be related to giraffes, D. xiezhi, which has fossils that show adaptation for fierce head-butting behavior. They are said to have one of the most durable skulls and thickest vertebrae of mammals. This behavior can also be observed in giraffes, which is why they may have evolved to have such long necks.

There's an ongoing theory that giraffes have evolved this way because of mating practices. Male giraffes are known to swing their necks, smashing their skulls into a challenging male, to assert their dominance. This behavior is seen throughout the animal kingdom, such as deer using their horns. It is a compelling theory as to why a giraffe's neck is like this.

[Prof. Tarma Amelia Black]

I was reminded of the Brontosaurus, when I looked at the picture of the giraffe.  That long neck ... but the legs are long and elegant, unlike the somewhat tree-like legs of the dinosaur. I had read that the Brontosaurus had developed that neck for grazing on the taller plants, as mentioned in the theory that you wrote about why giraffes have long necks.

 

I think that that is a viable theory, and that they might have started out with shorter necks, which eventually got a lot longer. What's really odd about the number of neck bones of the Brontosaurus versus the Giraffe is that the dinosaur has 11 vertebrae, compared to the 7 vertebrae of the Giraffe.  (Yes, I know the name was changed to something else, but really, the experts who changed the name seem like the experts who said that Pluto is not a planet .... ). (I also didn't do a lot of Googling to find out if there are varying numbers of 'official' bones of the dinosaur neck either. Seems like there is a lot of 'official' differences in the study of dinosaurs   )

[Artemisia Thorne]

This discussion also delves into intriguing legends. While evolution and natural processes are clearly proven, I think the legends that ancient cultures told to explain these are so beautiful. One African myth recounts that when God communicated with each species, the giraffe stretched her neck to hear more clearly. As a reward for this effort, she was bestowed with a long neck, enabling her to reach the leaves on the highest branches of the tallest trees. This legend serves as a metaphor for the notion that extra effort and attentiveness are deserving of special rewards.

Another legend proposes that the giraffe's extended neck symbolizes humility and patience. According to this narrative, the giraffe was initially fashioned with a short neck, akin to other animals. However, during a period of drought in the African savannah, when food became scarce, the giraffe exhibited exceptional patience and selflessness. According to the legend, the giraffe willingly permitted other animals to feed on the lower branches of trees, showcasing a remarkable level of humility. Impressed by this act of kindness, the gods decided to reward the giraffe by gradually elongating its neck. The giraffe's sacrifice and patience during challenging times earned it the ability to reach the abundant foliage at the tops of trees, ensuring its survival even in times of scarcity.

[Dibyarup James Potter]

The Brachiosaurus was a massive dinosaur that lived during the Late Jurassic Period, around 154 to 153 million years ago, estimates suggesting it could reach lengths of up to 85 feet (26 meters). Belonging to the sauropod group, Brachiosaurus is renowned for its distinctively long neck, reaching heights of around 40 feet (12 meters) or more. There are other sauropods such as the Brontosaurus and Diplodocus as well. All these dinosaurs are similar, and have a very long neck, similar to the giraffe. 

All these dinosaurs were herbivores, and that leads me towards a fascinating idea (which is contradictory to what the science says, coming to that later) that giraffes in fact are distant relatives of the dinosaurs, but during the extinction of dinosaurs, some of them survived somehow, and their genetic information got altered for the sake of survival and evolution, very slowly, over centuries, which led those animals to slowly evolve into mammals, and at some point that animal, which cannot be called a giraffe exactly, gave birth to the first modern day giraffe. 

Of course this is just a theory, and it is quite contradictory to the current scientific understanding of the topic, which is, all dinosaurs including the Brachiosaurus, Brontosaurus and Diplodocus were reptiles while giraffes are mammals. But my theory is not very far-fetched either, since we know that all modern day life evolved from one cell, and that means at some point all mammals, reptiles and other creatures have had the same ancestor, which further reinforces my idea that it is quite possible that some dinosaurs that managed to survive the mass extinction, had to undergo massive evolutionary changes.

[Hiya Debnath]

The long necks of giraffes can be attributed to three different theories: -

1. The theory of inheritance of acquired characters, given by Jean Lamarck, (postulates of Lamarckism) - Certain organs decrease in size and disappear whereas the need to adjust to environmental changes make new traits appear. These new traits and loss of organs are inheritable and passed on from generation to generation until the difference is too noticeable and the offspring is different enough from the first ancestor to be called a new species.

This theory explains why ducks have webbed feet, why snakes have no limbs, and why modern horses have the type of feet they have.

This theory, however, does not explain why the vestigial organs in humans, such as the appendix, still exist.

Also, August Weismann, performed an experiment in which he cut off the tails of rats for about 80 generations, but tailless rats were not born. This further disproves Lamarck's theory.

2. The theory of natural selection, given by Charles Darwin and Alfred Russel Wallace (theory of Darwinism) - This theory was based on Darwin's observation of animals and plants in Galapagos islands. It is also known as the theory of the survival of the fittest. It states that most species produce a large number of offspring, trying to continue their race. Out of these offspring, a few are born different, that is, with variations. Darwin says that variation is the law of nature and that some offsprings are automatically born with natural variations. However, environmental resources are limited and not all the offspring are able to survive due to the constant struggle for food, water, and other environmental resources. Offsprings with certain variations fare better in these struggles and adapt to the natural environment and the competition for resources because the variation that they are born with is more beneficial than others in the circumstances they are subjected to, e.g., long-necked giraffes are better able to survive than short necked-giraffes in places where grass is scanty and lots of grass-eating animals are competing for enough grass as food, because long-necked giraffes can feed themselves on leaves from tall trees that other animals can't reach and survive, whereas short-necked giraffes can't and will perish for lack of grass if there is too much competition for food. Eventually, the ones with unfavorable variations (such as short-necked giraffes) die out and the ones with favorable variations (such as long-necked giraffes) survive and create more offspring. This continues for generations until the long-necked giraffes are the majority of the giraffe population, and eventually, all giraffes are long-necked, naturally selected by nature. Although Darwin failed to explain why giraffes with different lengths of the neck were born in the first place, his theory was proved by artificial selection (on controlled breeding and artificially favoring certain traits for several generations, new species with only the favorable traits were formed).

Many people agree with Darwin's theory to this day.

To smooth out the disadvantages of Darwin's theory, a fresh theory called Neo-Darwinism was developed, which integrates Darwin's theory of natural selection and Mendel's theory of genetics by Gregor Mendel. This theory states that variations occur in the DNA, not in the individual, and thus are inheritable. This explains away the birth of the first long-necked giraffe as an accident that led to mistaken transcription of a giraffe's DNA in the giraffe's body and remained in the long-necked giraffe's DNA and kept being passed on to its offspring as well.

3. De Vries' Mutation Theory, given by HUGO DE VRIES, a Dutch botanist, based on his observations on the different types of Primrose (Oenothera lamarckiana)  - He postulated that certain sudden changes in the DNA structure, that occur accidentally when the body attempts to chemically transcript the information in the DNA, lead to emergence of mutations, or unique traits that do not exist in other organisms of the same species. Individuals with mutations are called mutants. The same mutations can randomly appear again and again, indeterminately. Eventually, there are enough mutants of a certain type, who inbreed with each other, and at one point, the mutation is common enough to be called a new species. This theory both successfully explains the source of variation and speciation (creating new species with a certain different trait) of a variation. This theory is therefore the most accepted theory in today's world, and I agree with this theory, too, because it explains both mutations and speciation. Disadvantages to De Vries' theory include the fact that evolution is a slow and gradual process while mutation is an abrupt, sudden change.

 

[Prof. Sirius Fudge]

I looked at some information regarding this discussion and found an image (see below) that made me understand and appreciate more the length of time involved in this evolution process. Millions of years have been the time talked about in this process of how the present giraffes have such long necks. It is amazing how features have changed over millions of years, evolving to different species.

 

 

The article also talked about the two factors already mentioned by previous posts in this thread. The need for survival of long necks to graze more food, to reach the spaces where there is less competition as well as the sexual preferences of female giraffes for long necks, further carrying the said gene along future members of species.

 

The article concluded that there are already existing long necks in the past millions of years in genetic ancestors of giraffes. They are not as long as those necks of present-day giraffes.

 

Source: https://www.sciencenews.org/blog/wild-things/how-giraffe-got-its-long-neck

[Janne Halla]

I always thought that it holds true that giraffes have long necks because of grazing and evolution. It seems to be the prevalent theory, so I was surprised this isn't the scientific consensus.

Most of the theories have been covered in previous posts, but I do find it interesting that one of them (mentioned in the introductory post) was that giraffes have long necks for fighting or rather, to defend themselves from shorter predators.

Male giraffes use their weighty skulls as clubs to whip around their necks. A giraffe's chances of winning a battle are higher when its neck is thicker and longer. Giraffes who win battles have a higher probability of procreating and giving birth to young.

It seems like a good argument in favour of long necks, especially if you couple it that being so tall lets a giraffe watch for predators, not only fight them.
It's interesting to see so many different theories! Maybe a little bit of each is true?