A team of evolutionary biologists, physicists and applied mathematicians say they know why eggs come in so many different models. In a report published in the journal Science on Thursday (US time), the scientists linked egg shapes to birds’ flight behaviour. Stronger fliers, such as swallows, had elongated or pointy eggs. Birds that couldn’t fly so far or fast had rounder, more symmetric ones.

The analysis revealed adaptations for an aerodynamic body had a “knock-on effect” for egg shape, Stoddard said. Pointy or elongated eggs don’t help a gravid bird fly, in other words. But the demands of powerful flight restructured internal organs. The abdominal cavity of the superior fliers became smaller, for example, forcing egg shape to change.

The ideas in the paper were “fascinating and significant,” said Russell, who was not involved in the new research. “The evidence that egg shape may be linked with morphological traits associated with flight ability across all birds opens a new chapter” in research, he said in an email.

The new analysis leaves room for other evolutionary egg influences, but those must act on a smaller scale, according to Stoddard. “Our study challenges some of the old assumptions about why eggs come in a variety of shapes,” she said. “On a global scale, across birds, we find that it’s not nest location or clutch size that predicts egg shape – it’s flight ability.”

Full: http://www.canberratimes.com.au/technology/sci-tech/scientists-say-they-have-worked-out-why-eggs-are-shaped-like-eggs-20170622-gwwt94.html

I was just listening to an interview about this on the wireless.

Bubblecar said:

A team of evolutionary biologists, physicists and applied mathematicians say they know why eggs come in so many different models. In a report published in the journal Science on Thursday (US time), the scientists linked egg shapes to birds’ flight behaviour. Stronger fliers, such as swallows, had elongated or pointy eggs. Birds that couldn’t fly so far or fast had rounder, more symmetric ones.

The analysis revealed adaptations for an aerodynamic body had a “knock-on effect” for egg shape, Stoddard said. Pointy or elongated eggs don’t help a gravid bird fly, in other words. But the demands of powerful flight restructured internal organs. The abdominal cavity of the superior fliers became smaller, for example, forcing egg shape to change.

The ideas in the paper were “fascinating and significant,” said Russell, who was not involved in the new research. “The evidence that egg shape may be linked with morphological traits associated with flight ability across all birds opens a new chapter” in research, he said in an email.

The new analysis leaves room for other evolutionary egg influences, but those must act on a smaller scale, according to Stoddard. “Our study challenges some of the old assumptions about why eggs come in a variety of shapes,” she said. “On a global scale, across birds, we find that it’s not nest location or clutch size that predicts egg shape – it’s flight ability.”

Full: http://www.canberratimes.com.au/technology/sci-tech/scientists-say-they-have-worked-out-why-eggs-are-shaped-like-eggs-20170622-gwwt94.html

Narrower hips would make better flight dynamics perhaps and they can only lay narrower pointer eggs

And yet they all just look like eggs, really.

buffy said:

And yet they all just look like eggs, really.

But fascinatingly different

Cymek said:

Narrower hips would make better flight dynamics perhaps and they can only lay narrower pointer eggs

Yes. I doubt it could be the other way around, where egg shape evolved to accommodate different shaped young. When hatching, birds usually chip away from the flattest, weakest part of the egg, so I’m guessing that they’re “across” the egg, which is rarely symmetrical IYKWIM.

> the scientists linked egg shapes to birds’ flight behaviour. Stronger fliers, such as swallows, had elongated or pointy eggs. Birds that couldn’t fly so far or fast had rounder, more symmetric ones.

That doesn’t make nearly as much sense as the standard explanation.

Swallow’s eggs are more conical and less symmetric to stop the rolling out of the nest. Swallow’s nests are very precarious places. Birds that nest on flat ground don’t have to worry about the eggs rolling out of the nest so have rounder more symmetrical shapes.

The greater the lack of symmetry, the greater the range of nesting sites available.

I would think those conclusions would be only part of the story, as birds nesting on narrow ledges generally have top shaped eggs to reduce the possibility of them rolling off the edge, something that evolution would certainly favour. Nature is not a linear progression of events, but adaptations to their environment of which flying long distances and the need for streamlined bodies is but one requirement.

mollwollfumble said:

> the scientists linked egg shapes to birds’ flight behaviour. Stronger fliers, such as swallows, had elongated or pointy eggs. Birds that couldn’t fly so far or fast had rounder, more symmetric ones.

That doesn’t make nearly as much sense as the standard explanation.

Swallow’s eggs are more conical and less symmetric to stop the rolling out of the nest. Swallow’s nests are very precarious places. Birds that nest on flat ground don’t have to worry about the eggs rolling out of the nest so have rounder more symmetrical shapes.

The greater the lack of symmetry, the greater the range of nesting sites available.

The swallows that nest with me have a typical shaped nest with a reasonably deep bowl in which the eggs have no way of rolling out.

Different swallow species have different egg shapes. Some are fairly conical and others are fairly symmetrical.

A bird species with possibly the most conical egg shape of all is the guillemot, which lays on small ledges on cliff faces with minimal nest.

mollwollfumble said:

> the scientists linked egg shapes to birds’ flight behaviour. Stronger fliers, such as swallows, had elongated or pointy eggs. Birds that couldn’t fly so far or fast had rounder, more symmetric ones.

That doesn’t make nearly as much sense as the standard explanation.

Swallow’s eggs are more conical and less symmetric to stop the rolling out of the nest. Swallow’s nests are very precarious places. Birds that nest on flat ground don’t have to worry about the eggs rolling out of the nest so have rounder more symmetrical shapes.

The greater the lack of symmetry, the greater the range of nesting sites available.

I suppose the capacity of flight means the capacity to seek more precarious locations becomes possible too.

monkey skipper said:

mollwollfumble said:

> the scientists linked egg shapes to birds’ flight behaviour. Stronger fliers, such as swallows, had elongated or pointy eggs. Birds that couldn’t fly so far or fast had rounder, more symmetric ones.

That doesn’t make nearly as much sense as the standard explanation.

Swallow’s eggs are more conical and less symmetric to stop the rolling out of the nest. Swallow’s nests are very precarious places. Birds that nest on flat ground don’t have to worry about the eggs rolling out of the nest so have rounder more symmetrical shapes.

The greater the lack of symmetry, the greater the range of nesting sites available.

I suppose the capacity of flight means the capacity to seek more precarious locations becomes possible too.

This was a large-scale study looking for global tendencies, and although they don’t deny other factors are involved, it seems the linkage with flight ability is very statistically significant.

Evening monkey.

I’m watching Invasion of the Body Snatchers for the umpteenth time for the cosiness of it, and then may go in search of a documentary.

I wonder whether birds that have problems with cuckoos have tried to produce an egg that couldn’t be pushed out of the nest?

So the birds developed an internalized aerodynamic system for egg production?

Tau.Neutrino said:

So the birds developed an internalized aerodynamic system for egg production?

As was suggested it is most likely all about the evolution specifics related to the purpose of the bird’s flight necessities.

roughbarked said:

I wonder whether birds that have problems with cuckoos have tried to produce an egg that couldn’t be pushed out of the nest?

With grappling hooks I presume. Cuckoos generally have at most a handful of species they parasitise where their eggs are similar in colouration and size. Some birds are a wake-up to the cuckoo and will push its egg out of the nest before it can hatch.

PermeateFree said:

roughbarked said:

I wonder whether birds that have problems with cuckoos have tried to produce an egg that couldn’t be pushed out of the nest?

With grappling hooks I presume. Cuckoos generally have at most a handful of species they parasitise where their eggs are similar in colouration and size. Some birds are a wake-up to the cuckoo and will push its egg out of the nest before it can hatch.

Indeed but is possibly an interesting thought within this sphere?

roughbarked said:

PermeateFree said:

roughbarked said:

I wonder whether birds that have problems with cuckoos have tried to produce an egg that couldn’t be pushed out of the nest?

With grappling hooks I presume. Cuckoos generally have at most a handful of species they parasitise where their eggs are similar in colouration and size. Some birds are a wake-up to the cuckoo and will push its egg out of the nest before it can hatch.

Indeed but is possibly an interesting thought within this sphere?

Being as most of target birds do not know the difference between their chicks and the cuckoo’s and continue to feed the single gigantic chick, natural selection would not take place as they do not understand their parasitation.

PermeateFree said:

roughbarked said:

PermeateFree said:

With grappling hooks I presume. Cuckoos generally have at most a handful of species they parasitise where their eggs are similar in colouration and size. Some birds are a wake-up to the cuckoo and will push its egg out of the nest before it can hatch.

Indeed but is possibly an interesting thought within this sphere?

Being as most of target birds do not know the difference between their chicks and the cuckoo’s and continue to feed the single gigantic chick, natural selection would not take place as they do not understand their parasitation.

It is indeed one of evolution’s conundrums.

roughbarked said:

PermeateFree said:

roughbarked said:

Indeed but is possibly an interesting thought within this sphere?

Being as most of target birds do not know the difference between their chicks and the cuckoo’s and continue to feed the single gigantic chick, natural selection would not take place as they do not understand their parasitation.

It is indeed one of evolution’s conundrums.

I think it is the cuckoo that has evolved to take advantage of the vulnerability of certain small birds. The small birds are just doing what they normally do.

PermeateFree said:

roughbarked said:

PermeateFree said:

Being as most of target birds do not know the difference between their chicks and the cuckoo’s and continue to feed the single gigantic chick, natural selection would not take place as they do not understand their parasitation.

It is indeed one of evolution’s conundrums.

I think it is the cuckoo that has evolved to take advantage of the vulnerability of certain small birds. The small birds are just doing what they normally do.

I’d also reckon this but are we in a small window of such an evolutionary process?

roughbarked said:

PermeateFree said:

roughbarked said:

It is indeed one of evolution’s conundrums.

I think it is the cuckoo that has evolved to take advantage of the vulnerability of certain small birds. The small birds are just doing what they normally do.

I’d also reckon this but are we in a small window of such an evolutionary process?

It is certainly very complex and there are many interactions that we don’t know.

I wonder how much egg shape is preserved over the millennia. The shape now wouldn’t be all that different to the shape of the eggs of dinosaurs such as velociraptor and protoceratops.