Eggs come from chickens and chickens come from eggs: that’s the basis of this ancient riddle. But eggs – which are just female sex cells – evolved more than a billion years ago, whereas chickens have been around for just 10,000 years. So the riddle is easily solved…or is it?
Taken at face value, there is no doubt that the egg came before the chicken. We tend to think of eggs as the shelled orbs laid by birds from which their chicks hatch – unless we eat them first. But all sexually reproducing species make eggs (the specialised female sex cells). That’s 99.99 per cent of all eukaryotic life – meaning organisms that have cells with a nucleus, so all animals and plants, and everything but the simplest life forms.
We don’t know for sure when sex evolved but it could have been as much as 2 billion years ago, and certainly more than 1 billion. Even the specialised sort of eggs laid by birds, with their tough outer membrane, evolved more than 300 million years ago.
As for chickens, they came into being much later. They are domesticated animals, so evolved as the result of humans purposefully selecting the least aggressive wild birds and letting them breed. This seems to have happened in several places independently, starting around 10,000 years ago.
The wild ancestor of chickens is generally agreed to be a tropical bird still living in the forests of Southeast Asia called the red junglefowl – with other junglefowl species possibly adding to the genetic mix. From these origins, humans have carried chickens around the world over the past two millennia or more.
So, eggs dramatically predate chickens. But to be fair to the spirit of the riddle, we should also consider whether a chicken’s egg predates a chicken. As humans consistently chose the tamest red junglefowls and bred them together, the genetic makeup of the resulting birds will have shifted. At some stage during this domestication process the red junglefowl (Gallus gallus) evolved into a new subspecies, Gallus gallus domesticus, AKA the chicken.
In practice, it is impossible to pinpoint the moment when this happened. But in theory, at some point two junglefowl bred and their offspring was genetically different enough from the species of its parents to be classified as a chicken. This chicken would have developed within a junglefowl egg and only produced the very first chicken’s egg on reaching maturity. Looked at this way, the chicken came first.
which best describe a secondary wave
Answer:
A type of seismic body wave in which rock particles vibrate at right angles to the direction of wave travel. These waves are the second fastest traveling seismic waves (after primary waves) and can travel through solids but not through liquids or gases. ...
why did NASA chose Jezero Crater as the landing site for Perseverance?? (2020)
Scientists believe the area was once flooded with water and was home to an ancient river delta.Conceivably, microbial life could have lived in Jezero during one or more of these wet times.
There are many technologies that reduce the amount of carbon emissions into our atmosphere. Identify some example of these technologies.
Answer:
The hybrid cars
Explanation:
It reduce the carbon emissions because it use other types of energy such as calorific when the car brakes friction is created and the car motor serves as a converter to electrical energy to take them to the car batteries and put it to use
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How does a human arm compare with an iguana's?
By comparing a human arm with an iguana arm, we have the following differences.
The human arm is not used in walking, while the iguana arm is used in walking because the iguana is naturally quadrupedal.
The human arm is used in lifting load, while the Iguana arm is not.
However, both human arms and iguana arms have five fingers.
They both have upper and lower arms.
An iguana is a form of a non-venomous lizard.
Hence, in this case, it is concluded that the human arm with an iguana arm has similarities and differences.
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Name the general. Describe how he attacked Shivaji.
What type of fault is being demonstrated in the above illustration?
( )
A Strike-slip fault
B Normal fault
C Reverse fault
It is 7:40 pm in Sydney NS.
What time is it in:
St John's?
Prince Rupert?
Toronto?
Thompson?
Answer:
St John's is 7:19 PM
Prince Rupert is 2:49 PM
Toronto is 5:49 PM
Thompson is4:49 PM
Explanation:
:)
HELP HELP HELP DUE IN 30 MINS
Answer:
copernicus's idea of the solar system had an idea of the sun in the middle aka heliocentric model, and Ptolemy's model aka the geocentric model has the Earth located in the center
Explanation:
I had this lesson earlier this school year
Which modern technology allows populations to survive extreme droughts and lack of fresh drinking water?
Answer:
no hablo ingles
Explanation:
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Plant life in wetlands is not
different from plant life In other areas.
True
False
Answer:
false
hope it is helpful to you
Does anyone know the answers to these
Answer:
Clouds forming high pressure and sunny clear skies low pressure
Explanation:
why does thunder snow happen
Which is the safe country to travel in Africa
Bot Botswana is the safest country in Africa and 30th safest country in the world.
HELP ME!!!!!
The jet stream flows from east to west across the United States and Europe.
True
False
Answer:
False
Explanation:
Volcanic eruptions are catastrophic events that can lead to loss of life. Which measure should people living near the region of an active volcano take to minimize the loss of life?
Question 10 options:
a.Install devices to monitor the levels of gases emitted by the volcano.
b.Build houses with no vents to avoid contact with lethal gases.
c.Use seismographs to predict volcanic eruptions.
d.Build tall houses with steel reinforcements to withstand tremors.
Answer:
Option C, Use seismographs to predict volcanic eruptions
Explanation:
People living near volcanoes proximity are at high risk during the eruption period of volcanoes. As the volcano erupts it releases harmful gases and also the hot molten lava flows out of it thereby disrupting every thing that comes in its way.
If people living in such areas are able to get pre information of volcanic eruptions then they can get time to shift to new safer place.
Hence, option C is correct
Which group in Guatemala mixes traditional religious rituals with European traditional religious rituals?
Answer:
If thass yo questin den yeee but if it’s not bye
Explanation:
Which indigenous group on Guatemala mixes traditional religious rituals with European ones? Mayans.
draw up a turist profile
Answer:
Hi Just Wanna Say “ Long Live XXXTentacion “ If udk who he is he’s a rapper who was shot and killed on June 18 2018 He Is A Legend. Would appreciate it if you liste to him in Spotify
Explanation:
11. The two images represent two different methods of raising livestock in the United States. Which of
the following statements most accurately compares these two agricultural practices?
a. Cattle ranching is a more economically friendly way to raise livestock than using feedlots
because less infrastructure is needed
b. Feedlots require more space than cattle ranching does, which reduces profits due to the cost of
the land
C. Consumers prefer to pay higher prices for grass-fed beef than for corn-fed beef raised in
feedlots because of the environmentally friendly practices associated with grass-fed beef.
d. Feedlots can minimize costs associated with livestock production because feedlots do not use
as much space as cattle ranching
e Feedlots require less food consumption by the cows than cattle ranching because the livestock
are grazing on available grass in the pastures
Answer:d
Explanation:
The two images represent two different methods of raising livestock in the United States. Which are Feedlots can minimize costs associated with livestock production because feedlots do not use as much space as cattle ranching.
What are cattle feedlot and cattle ranching?
Cattle feedlot is a type of animal feeding operation used for animal farming, beef cattle, horses, swine, sheep, turkeys, chicken, or duck prior to slaughter.
Ranching is an activity that is used for raising cattle such as horses, sheep. It covered a lot of areas. Cattle farming is increasing the effect of greenhouse gases and climate change.
Therefore the correct option is D.
Learn more about Cattle feedlot and ranching here:
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How have humans helped the
Isle Royale Ecosystem?
Answer:
Even our mammalian brethren have found getting to Isle Royale difficult. Of the 50 or so mammal species that live on the mainland, only about 20 mammal species call Isle Royale home. And several that once called it home have since gone extinct – caribou, coyote, sharp-tailed grouse. Humans have never regularly lived year-round on Isle Royale.
School Questions
1. What should you do if you feel an earthquake happening?
2. Explain why a rural area might be a safer place to experience an earthquake than a large city.
3. Describe the three kinds of waves that are produced in an earthquake.
Answer:
Ans.1. If you are indoors, drop and take cover under a sturdy table or other furniture. Hold on to it and stay put until the shaking stops.
Stay clear of items that can fall and injure you, such as windows, fireplaces and heavy furniture.
Stay inside. You may be injured by breaking glass and falling objects if you run outside.
If you are at the coast, walk to higher ground away from the ocean as soon as it is safe for you to move.
If you are driving, move your car as far out of the normal traffic pattern as possible and stop if it is safe. Stay away from structures or objects that could fall on you, such as bridges, overpasses, light posts, power lines or trees. Stay inside your car.
If you are in the mountains, or near unstable slopes, be alert for falling rocks, trees or landslides that could be loosened by the earthquake.
Ans.2.Rural/Urban area: Rural areas have fewer people and fewer buildings so the size of the disaster is smaller. Distance from the epicentre: The closer a town or city is from the epicentre the more damage will be caused because of the strong seismic waves.
Ans. 3 There are three basic types of seismic waves – P-waves, S-waves and surface waves. P-waves and S-waves are sometimes collectively called body waves.
Answer:
Ans.1. If you are indoors, drop and take cover under a sturdy table or other furniture. Hold on to it and stay put until the shaking stops.
Stay clear of items that can fall and injure you, such as windows, fireplaces and heavy furniture.
Stay inside. You may be injured by breaking glass and falling objects if you run outside.
If you are at the coast, walk to higher ground away from the ocean as soon as it is safe for you to move.
If you are driving, move your car as far out of the normal traffic pattern as possible and stop if it is safe. Stay away from structures or objects that could fall on you, such as bridges, overpasses, light posts, power lines or trees. Stay inside your car.
If you are in the mountains, or near unstable slopes, be alert for falling rocks, trees or landslides that could be loosened by the earthquake.
Ans.2.Rural/Urban area: Rural areas have fewer people and fewer buildings so the size of the disaster is smaller. Distance from the epicentre: The closer a town or city is from the epicentre the more damage will be caused because of the strong seismic waves.
Ans. 3 There are three basic types of seismic waves – P-waves, S-waves and surface waves. P-waves and S-waves are sometimes collectively called body waves.
Explanation:
How many countries is Europe made of
Answer:
Five European countries rank in the top ten of the world's largest national economies in GDP (PPP). This includes (ranks according to the CIA): Germany (6), Russia (7), the United Kingdom (10), France (11), and Italy (13). There is huge disparity between many European countries in terms of their income.
Explanation:
Answer:
50 Countries
Explanation:
Europe is shared by 50 countries. By the conventional definition, there are 44 sovereign states or nations in Europe. Not included are several countries namely Turkey, which occupies only a small part of East Thrace on the European Balkan Peninsula.
What is the absolute location of the equator?
Answer:
The Equator is the line of 0 degrees latitude. Each parallel measures one degree north or south of the Equator, with 90 degrees north of the Equator and 90 degrees south of the Equator. The latitude of the North Pole is 90 degrees N, and the latitude of the South Pole is 90 degrees S
Explanation:
Look at the map below. All of the following climate regions are located in Central Asia except the __________ region.
A. Marine west coast
B. Humid continental
C. Semiarid
D. Arid
Answer:
Humid Continental
Explanation:
Answer:
A. Marine west coast
Explanation:
Right on Egde 2021
Which region in Africa can rainforests be found? North or central Africa?
Answer:
Rainforests are primarily found in Central Africa.
Answer:
Central Africa
Explanation:
North Africa has an arid desert climate, with high temperatures and very little precipitation. Instead of spring, summer, fall, and winter, most countries south of the Sahara Desert have dry and rainy seasons
hi can anyone please help me with this?
Answer:
leg = 7
hyp: 7√2
Explanation:
leg: 7tan45 = 7
hyp: 7/cos45 =[tex]7\sqrt{2}[/tex]
Is the oceanic crust above or below the continental crust?
Answer:
Above
Explanation:
which fact about the moon, as seen from the earth, is eidence that the amount of time the moon takes to complete one rotation and one revolution are nearly identical
Answer:
C). We always see the same side of the Moon from Earth.
Explanation:
As per the question, the fact regarding 'witnessing the same side of the moon' substantiates the time taken by the moon for accomplishing the process of rotation and revolution is almost the same i.e. 27 days( approx.). This locked equal tidal rate of spin causes the identical time for both the process is known as synchronous rotation which causes us to see the same side of the moon from the Earth. Thus, option C is the correct answer.
Enlist some places from where gold is mined.
Answer:
China, Australia, South Africa
Explanation:
About 244,000 metric tons have been mined and most of it came from that top3 countries
Find c(3) in the sequence given by c(1)=20 c(n)=c(n−1)−17 c(3)=
Answer:
( -14 ) .................
Explanation:
c(1) = 20
c(2) = c(1) - 17 = 20 - 17 = 3
c(3) = c(2) - 17 = 3 - 17 = ( -14)