Hello and welcome to this lesson from the Oak National Academy.

This lesson is on selective breeding and human food security.

It's taken from the unit, fossil evidence, selective breeding, and explaining evolution.

Hiya, I'm Mrs. Wheate and I'm gonna be your teacher for today's lesson.

By the end of today's lesson, you'll be able to explain what is meant by selective breeding and why it's important for human food security.

Let's have a look at our keywords.

Today's lesson has got five keywords, and we'll run through them very quickly now.

Selective breeding, the process in which humans choose individuals with desirable traits and mate them in order to make offspring with these desirable traits.

Crop, plants grown on a large scale for food or profit.

Domesticated, an animal that has been tamed and is kept as a pet or on a farm.

Farm animal, animals that are kept on farms for food or work.

Food security, a measure of the quantity and quality of food available to support households or whole communities.

So, don't worry if you didn't retain all of that.

I'm not expecting you to have memorised that just from me reading it out loud.

And we just put them at the front here so you're more familiar with the terms as they come up.

And if you wanna pause the video now, you're free to do that if you wanna write them down and think about them in a bit more detail.

So I'll be quiet for five seconds so you can read through them again, or if you wanna pause, then click play when you're ready to move on with the lesson.

Today's lesson is in two parts.

First of all, we'll talk about selective breeding, what it is, and some key examples of selectively bred plants and animals.

Then after that, we'll talk about selective breeding and how important it is to human food security.

But first of all, let's talk about what selective breeding is.

So, selective breeding.

You wouldn't have a wild wolf in your home, but you might have a pet dog.

Pet dogs have descended from wolves using selective breeding over many thousands of generations, resulting in the breeds of dogs we see today.

Selective breeding is when humans choose organisms with desirable traits and mate them in order to make offspring with these desirable traits.

So if we look at wolves, wolves are pretty aggressive, don't like humans very much, not very obedient.

So how wolves became dogs, or some wolves became dogs anyway, is that humans chose wolves that were more obedient and less aggressive, mated them together, bred them together, and then repeated that thousands of times.

And eventually, you got less aggressive offspring, more obedient offspring and we have the tame, which means obedient and not very aggressive, breeds of dogs that we have today.

So, that's one example of how selective breeding works.

Selective breeding isn't just limited to wolves and dogs.

Many of the foods we eat today look completely different to how they appeared hundreds of years ago.

Humans have used selective breeding to enhance the desirable characteristics of the plants and animals we eat.

So, we have this picture of an animal which is extinct.

It's a wild aurochs.

So these wild aurochs, which were huge, aggressive animals, were selectively bred slowly over time to become cattle.

So this is a selectively bred cow.

This cow is used for dairy, so for its milk.

Cows are pretty placid.

They let us milk them.

You wouldn't wanna try and milk a wild animal.

So again, this is a process that took thousands of generations to go from wild animal to a tame farm animal.

Let's look at an example with plants.

So, these are what carrots look like in the wild.

And carrots have also been selectively bred over thousands of generations to become like a carrot that you would see in the supermarket.

Plants are selectively bred for all sorts of reasons.

To enhance their nutritional value, to increase the amount of calories they have, or to just improve their appearance or texture.

Let's see if we understood that.

Which of the following apply? Selective breeding can be carried out on A, plants only, B, animals and plants, or C, animals only.

Take five seconds or pause the video if you want more thinking time.

Click play when you're ready to see the answer.

Let's take a look at the answer.

It is B, selective breeding can be carried out on animals and plants.

Let's look at some more examples.

Crops are plants grown on a large scale for food, like carrots, or for profit, like flowers.

We're just gonna focus on food today though.

The crops we eat have been selectively bred to enhance the proportion of the plant that is edible and to improve taste.

So here, we have the wild mustard plant, also called the wild cabbage plant.

And you wouldn't believe how many of the vegetables that we eat are descended from these plants.

So, some farmers chose to enhance the leaves on the wild mustard plant and that created cabbage and that created kale.

Other people chose to enhance the flower buds on these plants, and that became broccoli and cauliflower.

So, all of these plants are the same species, brassica oleracea, but they've been selectively bred over generations and generations and generations to have really different characteristics.

Just like how dogs, canis lupus familiaris, that's the species name, they are all the same species, but they have been selectively bred in different parts of the world for different purposes.

So they are all the same species.

Dogs are all the same species.

These vegetables, these plants here are all the same species, but it's selective breeding that has created these different types that's made them so, so different from each other and from the original wild plant.

So that was another plant example, let's look at some more animal examples.

Humans have domesticated many wild animals in order to farm them.

And that word domesticated again, is to do with reducing aggression in animals and increasing obedience through selective breeding.

The animals we eat have been selectively bred to increase the amount of meat and other products, like eggs or milk, that they produce.

If you think about it, if you're a farmer, do you want a scrawny chicken that doesn't have very much meat on it? That's not gonna make you very much money.

That's not gonna be very good at feeding your family.

You want a chicken that has the most meat on it, so you make more money when you sell it at a market or you have more meat to feed your family.

So for chickens, chickens are bred for their meat and their eggs.

We've got some sheep here.

Sheep have been selectively bred for their meat and their wool.

So again, to have more muscle, which is what primarily makes up meat.

And we also farm sheep and lambs for their wool, in order to make clothing and textile items. Okay and we've got cattle.

Cattle are selectively bred for their meat and their milk.

All of these animals will look very, very different from the wild animal they're originally domesticated from.

And that's because of selected breeding.

So animals haven't just been selectively bred for some people to eat, they've also been selectively bred to enhance the traits that allow them to work.

So we've got some cattle and we've got some horses here.

So they've both been selectively bred in order to help pull heavy farm equipment.

And that means more farming can get placed, again so the farmer can make more money or just feed their family better.

And dogs are another example of an animal that's been selectively bred for work.

Dogs can help herd other farm animals, and again, that's through selective breeding.

Not all breeds of dogs will do that.

So this example is a collie.

Try getting a chihuahua to herd some sheep, probably not gonna end very well.

So, a collie is an example of a dog that's been selectively bred and also, like trained by human beings in order to be really good at doing work that helps increase the farm's productivity.

Okay, let's see if you understood that.

True or false, the crops and farm animals we eat today are the same as the ones humans ate thousands of years ago.

Is that true or is that false? You can take five seconds or you can pause the video if you want some more thinking time.

Click play when you're ready to see the answer.

That is false.

Okay, but why is it false? Let's justify that answer.

Is it false because, crops and farm animals become more suitable for farming naturally over time? Or is it because humans use selected breeding to enhance the desirable characteristics of crops and farm animals? Again, take five seconds or pause the video if you want a bit more time to think.

It is B.

Crops and farm animals don't just naturally or magically become better for farming.

This is a deliberate choice that human beings have made and they've used selected breeding in order to enhance these desirable characteristics.

Well done if you got that right.

Let's take a look at the process of selected breeding.

So first of all, we need to select two individuals with the desired characteristics, the traits that you're interested in.

Then, you breed them together.

In crops this is called cross pollination.

So pollen from one plant is transferred to another plant.

For animals, artificial insemination can also be used to ensure that the chosen male and the chosen female are actually the ones that reproduce.

So artificial insemination involves taking semen from a male animal and inserting it into the female animal.

Okay, a variety of offspring will be produced, select the offspring with the desired characteristic.

Number four, breed them together.

So, same process as what we talked about in number two again.

And then repeat for several generations until all the offspring have the desired characteristic.

Let's see if you understood that.

Put these steps in order to describe the process of selective breeding.

You can use a step more than once or not at all.

A, select two individuals at random.

B, select the offspring with the desired characteristic.

C, repeat for several generations until all the offspring have the desired characteristic.

D, breed them together.

E, select individuals with desired characteristics.

Take five seconds or pause the video if you want more thinking time.

Click play when you're ready to see the answers.

Let's look at the answers.

So, the first step of selective breeding is selecting two individuals with the desired characteristics.

The second step is breeding them together or mating them together.

The next step, selecting the offspring with the desired characteristic.

After that, you breed them together.

And finally, you repeat this for several generations until all the offspring have the desired characteristic.

So A wasn't used at all.

In selective breeding, you don't choose the individuals at random.

It's a very deliberate choice which individuals you're choosing.

Well done if you got that right.

Selective breeding can cause traits to become more or less common.

So if we look at a couple of examples of that.

So, corn has been selectively bred to be larger and have more kernels, so they have a high nutritional value.

So that's an example where selective breeding has enhanced, made a trait bigger.

Many breeds of cattle, however, have been selectively bred to reduce their horn size, and that makes them much safer to farm.

Think about it, do you wanna be working with every single day an animal with massive horns? Probably not.

So this is an example of highland cows and they're a breed of cow where the female, the cow still has horns, whereas most breeds of cow that you would see kind of on a farm have been bred so that they don't have horns anymore, again, to make it safer for the farmer.

Let's see if you understood that.

This is a very common example of a question about selective breeding.

You're given an animal or a plant, sometimes you've heard of it, maybe you won't have heard of it, and you have to describe how it was selectively bred.

So let's do the first one together and then you're gonna have a go at the second one by yourselves.

So first question we'll do together is describe how to selectively breed a sweeter watermelon plant.

So, the steps for that would be choose the two sweetest watermelon plants available and see how I've taken the generic steps for selective breeding and I've made it specific to the context of the question, which is the watermelon plant, and we're selecting for sweetness.

Number two, cross pollinate them.

That step is specific to whether you're talking about an animal or a plant.

You could also say breed them together, that works for animals or plants.

Step three, select the sweetest offspring.

Again, that's specific to the context of the question.

We're selectively breeding for sweetness in this example.

Four, cross pollinate them.

Five, repeat for several generations until all the plants are sweet.

Okay, let's see if you can have a go at this one by yourself.

So, describe how to selectively breed an avocado plant with a smaller seed.

So remember to use the context of the question in your answer.

You can take five seconds now to think about it.

Or if you want some more thinking time, please pause, click play when you're ready to see the answer.

Okay, how was that? Let's go through the answers.

Number one, choose the avocado plants with the smallest seeds.

Two, cross pollinate them.

Three, select the offspring with the smallest seeds.

Four, cross pollinate them.

And then five, repeat for several generations until all the plants have smaller seeds.

Well done if you got that right.

Let's have a go at our first practise task.

Answer the question, complete the task below.

Number one, what is selective breeding? Number two, give two examples of crops and the traits they have been selectively bred for.

Number three, give two examples of farm animals and the traits they have been selectively bred for.

Number four, describe in steps how dogs have been selectively bred from wolves to reduce their aggressiveness.

So you need to pause the video here to give yourself enough time to think about those questions and to write down your answers.

Click play when you're ready to see the answers.

Good luck.

Okay, let's see how you did.

Number one, what is selective breeding? Selective breeding is when humans use organisms with desirable traits and mate them in order to make offspring with these desirable traits.

Number two, give two examples of crops and the traits they have been selectively bred for.

There's so many things that you could have put.

You didn't have to just write something that was off the slides.

If you have, totally fine, that's acceptable, but there are so many different answers to this question, I can't possibly write all of them, okay? So, if you've written a plant that people regularly eat, it's pretty much guaranteed it's been selectively bred.

So if you've written about that, it's probably right.

But these are the examples that I went for.

So, avocados have been selectively bred to reduce the size of their seeds.

Corn kernels have been selectively bred to be larger and increase the size of their kernels.

Okay, well done if you got that right.

Okay, question three.

Give two examples of farm animals and the traits they have been selectively bred for.

Again, lots of farm animals you could have put.

So, these are just two things that you could have said.

So chickens to produce more eggs and cattle to reduce the size of their horns.

Okay, number four.

Describe in steps how dogs have been selectively bred from wolves to reduce their aggressiveness.

Number one, choose the wolves that are the least aggressive.

Two, breed them together.

Three, select the least aggressive offspring.

Four, breed them together.

Five, repeat for several generations until all the offspring are less aggressive.

Oh, in steps two and four, if you talked about artificial insemination, that's correct too.

Well done if you got that right.

We've completed the first part of today's lesson.

We talked about selective breeding, described how it works, and we talked about some key examples of selectively bred crops and farm animals.

Now, we're gonna talk about selective breeding, and it's importance in human food security.

Food security is a measure of the quantity and quality of food available to support households or whole communities.

So in the UK, we are used to having fully stocked supermarkets.

So food security isn't something you really have to think about very much.

Maybe you've been to supermarket one time with your parents, you've noticed like, oh, there's not as much this on the shelf.

There's not as much that on the shelf.

And that can be for tonnes of reasons.

The climate of where our food is grown, for example, a lot tomatoes we eat come from Spain, so if Spain has been super, super, super hot one season, maybe we won't have as many tomatoes in the store.

But generally speaking, we can get pretty much anything we want anytime we want.

We're so fortunate.

And this isn't the case all across the world and a shortage of food can lead to poor health and starvation.

So food security, making sure that access to good quality food is secure, is super, super important.

Something that affects human food security is the size of the population you are trying to feed.

You can see on the graph below here that the human population has dramatically increased over the last few thousand years, with a particularly dramatic rise since around the 1700s.

Reproduction has had to dramatically increase in order to feed the billions of people now on the planet.

So, although there are thousands of edible plants in the world, most of the energy we need to survive comes from a very small number of plants.

So around the world, these are the most commonly eaten foods.

So rice, wheat, and corn make up to two thirds of the world's food intake.

Two thirds of the calories that we eat come from these really important crops.

They're sometimes called staple crops.

All of these important crops have been modified by selective breeding in order to increase food production.

Let's see if you understood that.

Complete the sentences about food security.

Food security is a measure of the blank and blank of food available to support households or whole communities.

The population has blank over the last thousands of years.

Blank blank has helped increase the amount of food available and increased food security.

Take five seconds or pause the video if you want more thinking time.

Click play when you're ready to see the answer.

Okay, let's take a look at the answers.

Food security is a measure of the quality and quantity of food available to support households or whole communities.

The human population has increased over the last thousands of years.

Selective breeding has helped increase the amount of food available and increased food security.

Well done if you got that right.

Here are some of the ways that plants and animals have been selectively bred in order to help food security.

So, one way is that they've been made easier to farm or safer to farm.

If we think about our example of the highland cow, in most breeds, the cow, the female, doesn't have horns.

The highland cow is one of the few examples of a cow that does have horns, and this has been done to make it safer for the farmer to farm the animals.

Another thing that's been done is to increase the edible parts of the crops.

So we talked about corn and how the kernels of corn, the part that we eat, we don't eat kind of the wrapper on the outside of the corn, which is like the husk, the leaves that protects the inside.

We don't eat that part.

The kernels, the part that we do eat, have been selectively bred to be as big as possible, so that gives us more calories and more nutrition.

So, another way is increasing the muscle mass of farm animals.

So below, we have some Belgian blue bulls, and these are another breed of cow, so same species as the highland cow above it, but they look really different, right? And they have a huge muscle mass.

And well, the muscle is the part of the animal, some of the part of the animal that we eat.

And so if an animal has more muscle, then there's more meat on it.

You can increase pest resistance in crops.

That's really important.

Crops can be really, really devastated by pests or by insects eating the crop and so selectively breeding in resistance to that means that farmers have a higher yield, so they have more crops to harvest when it comes to harvest time.

You can shorten the growing time of crops so they can be harvested sooner.

So instead of taking six months to grow, maybe now it takes three months to grow so you can grow more batches of a crop in a year, make more money, and also produce more food.

And another example is crops have been bred to be able to grow in poorer quality soil.

So you can grow them in places that you otherwise might not have been able to grow them.

So, these are just a few of the ways.

There's tonnes and tonnes of ways that animals have been and plants have been selectively bred.

These are just some of the ways that help food security.

So let's look at one example of a really important crop, wheat, in lots of detail.

Before selected breeding, wheat plants grew very tall, often over 1.

6 metres in height.

This made them really easily knocked over by the winds and caused the grain to fall to the ground.

So if we look at my diagram, which is showing, or my photo, which is showing the different parts of the wheat plant.

We have the stem at the bottom, we have the head of the wheat, and then an individual part of that is called the grain and grain is the part that we eat.

It gets ground really fine and that becomes flour, so we can make things like bread.

So if this grain is being knocked and scattered to the ground, that means that they could rot or they could be eaten by animals before they're able to be harvested.

So that means that less wheat is harvested, so there's less food available.

An American scientist called Norman Borlaug solved this problem using selective breeding.

He bred two different varieties of wheat together, a tall variety that produced lots of grain and a dwarf variety with a shorter and thicker stem that wasn't knocked over in the wind.

This new variety of wheat, along with other advances in agriculture, were part of this period of time called the Green Revolution, a time of technological advancement, which led to massively increased crop yields around the world.

This variety of wheat, the one that Norman Borlaug had selectively bred, led to a dramatic increase in wheat production and saved millions of people from starvation.

In 1970, Norman Borlaug won the Nobel Peace Prize for preventing world hunger and famine, which is amazing.

So, hopefully you can see that, not just in terms of selective breeding, but in terms of science in general, how useful science can be to the world.

This is such an important thing that happened and saved millions of people's lives, so incredible.

And again, a really important example for selective breeding.

Okay, let's see if you understood that.

Norman Borlaug increased food security by, A, selectively breeding a taller wheat plant.

B, selectively breeding a shorter wheat plant.

C, selectively breeding a wheat plant with a thicker stem.

Take five seconds or pause the video if you want more thinking time.

Click play when you're ready to see the answer.

Let's look at the answer.

So, B is correct.

The selectively bred plant was shorter and C is correct.

It also had a thicker stem.

And both of these qualities meant it was less likely to be knocked over in the wind.

And so come harvest time, there was more grain to be harvested.

Well done if you got that right.

This is our final practise task for today's lesson.

Answer the question and complete the task below.

Number one, what is human food security? Number two, state two ways in which selective breeding has improved human food security.

Number three, explain the importance of selective breeding to human food security.

And number four, describe the steps Norman Borlaug took to selectively breed a new, shorter variety of wheat.

So, you'll need to pause the video now to give yourself enough time to respond to those questions.

Click play when you're ready to see the answers.

Good luck.

Let's go through the answers.

Answer the question and complete the task below.

Number one, what is human food security? Food security is a measure of the quality and quantity of food available to support households or whole communities.

Number two, state two ways in which selective breeding has improved human food security.

So there's lots of things you could have put.

These are just some that I picked out.

Making crops and farm animals easier to farm, increasing the edible parts of the crops, increasing the muscle mass of farm animals, increasing pest resistance in crops, or you could have written insect resistance in crops.

Shortening the growing time of crops so they can be harvested sooner.

Crops have been bred to be able to grow in poorer quality soil.

So, any of those, but this isn't an exhaustive list.

There were other examples of things you could put as well.

So don't worry if you think, oh, I didn't put that down.

Your answer could be correct, I just couldn't include everything.

Right, moving on.

Number three, explain the importance of selective breeding to human food security.

Selective breeding has helped dramatically increase the amount of food that could be produced, which makes it more likely there is food available for whole communities.

Right, number four.

Describe the steps Norman Borlaug took to selectively breed a new, shorter variety of wheat.

A variety of wheat that produced a large amount of grain and a variety of wheat with a shorter, thicker stem were selected.

They were then cross pollinated.

The offspring that produced the most grain and had a short, thick stem were selected.

They were then cross pollinated.

This was repeated for several generations until all the plants produced had lots of grain and had short, thick stems. Well done if you got that right.

We have come to the end on our lesson about selective breeding and human food security.

Well done on all your hard work.

Let's summarise what we've learned to help us remember it.

Selective breeding is when humans choose organisms with desirable traits and breed them in order to make offspring with these desirable traits.

The crops and farm animals we eat have been selectively bred to enhance their desirable characteristics.

Food security is a measure of the quantity and quality of food available to support households or whole communities.

Selective breeding has increased food security by massively increasing crop yields.

Great work today.

I hope I see you really soon for our next lesson.