PA4 Teeth and diet

Summary

This lecture explores the dental adaptations of primates, highlighting their generalized dentition that allows for a varied diet, crucial in arboreal environments. Primates exhibit dietary plasticity, with most being omnivores. The script delves into dental formulas, explaining the differences between the primitive 2/1/3/3 and the derived 2/1/2/3, and discusses unique primate dental features like the tooth comb of prosimians and the diastema in apes and some monkeys, which accommodate large canines for social and dietary reasons.

Takeaways

• 🦷 Primates have a generalized dentition that allows for a varied diet, including a wide range of plant foods available at different times of the year.
• 🌳 The arboreal environment of primates necessitates dietary plasticity, as reliance on a single plant source is impractical due to seasonal availability.
• 🍎 Most primates, including humans, are omnivores, consuming both animal and plant matter, with some specializing in hundreds of different fruit types.
• 🔍 The dental formula is a method used by biologists to describe the teeth of primates, categorizing them into quadrants of the mouth.
• 🔢 Two common primate dental formulas are 2/1/3/3 (primitive) and 2/1/2/3 (derived), with differences indicating evolutionary adaptations.
• 🦷🌱 The 2/1/3/3 formula is found in New World monkeys and prosimians, while the 2/1/2/3 formula is seen in Old World monkeys, apes, and humans.
• 🦷🔑 Each type of tooth serves a specific function: incisors for snipping, canines and premolars for tearing, and molars for crushing and grinding.
• 🦷🦷 Some primates, particularly prosimians, have a tooth comb, a unique adaptation for grooming and processing food.
• 🦍🐒 Ape and some monkey species have large gaps called diastema, which accommodate their large canines, facilitating social behaviors and dietary needs.
• 🦷💪 Large canines in primates, such as baboons, are often related to their omnivorous diet and social behaviors, including competition and defense.
• 👨‍🏫 The script emphasizes the importance of understanding primate dentition for insights into their evolutionary history, diet, and social behaviors.

Q & A

What adaptation allows primates to eat a wide variety of foods?

Primates have a very generalized dentition, which enables them to eat a wide variety of plant foods and other items, adapting to the availability of different foods throughout the year.

Why is it important for primates to have a diverse diet in an arboreal environment?

In an arboreal environment, relying on a single kind of plant or a few plants is not feasible due to seasonal availability. A diverse diet allows primates to survive by consuming different plants that are ripe at different times of the year.

What is the term used to describe the dental formula of a creature?

The term used to describe the dental formula of a creature is 'dental formula,' which is a method biologists use to categorize and count the teeth in each quadrant of the mouth.

What are the two general dental formulas found in primates?

The two general dental formulas found in primates are 2/1/3/3, which is the primitive formula, and 2/1/2/3, which is the derived or specialized dental formula.

Which primates have the primitive dental formula of 2/1/3/3?

The primitive dental formula of 2/1/3/3 is found in modern New World monkeys and prosimians, such as lemurs, pottos, and other rosimians that live in Africa and Asia.

What is the significance of the derived dental formula 2/1/2/3 in primates?

The derived dental formula 2/1/2/3 is present in Old World monkeys, all apes, and humans, indicating a more specialized dentition compared to the primitive formula.

What are the functions of the different types of teeth in primates?

Incisors are used for snipping or biting off chunks, canines and premolars are used for tearing, and molars are used for crushing and grinding food.

What is a tooth comb, and which primates possess this feature?

A tooth comb is a dental feature where the front six teeth of the lower jaw project forward at a 90-degree angle. This feature is found only in prosimians, such as lemurs and ringtail lemurs.

What is the purpose of the diastema in the dentition of some primates?

The diastema, or large gaps adjacent to the canines, accommodates the large canines found in many apes and some monkeys, allowing them to open and close their mouths without interference.

Why do some primates, like baboons, have large canines?

Large canines in primates like baboons are an adaptation related to their omnivorous diet, allowing them to tear meat, and also serve social purposes, such as competition between males or defense.

How does the dental formula 2/1/3/3 differ from 2/1/2/3 in terms of the number of premolars?

The dental formula 2/1/3/3 indicates three premolars, while the formula 2/1/2/3 indicates two premolars, reflecting a difference in the structure and possibly the diet of the primates with these formulas.

Outlines

00:00

🦍 Primates' Teeth and Diet Adaptation

This paragraph discusses the generalized dentition of primates, highlighting its importance for a varied diet. Primates can consume a wide range of plant foods, which are available at different times of the year, thus requiring a 'Swiss Army mouth' for diverse chewing needs. The paragraph introduces the concept of dietary plasticity and the omnivorous nature of many primates, including humans. It also explains the dental formula used by biologists to describe the teeth of creatures, focusing on the two common primate dental formulas: 2/1/3/3 (primitive) and 2/1/2/3 (derived). The explanation includes a breakdown of the teeth in a quadrant of the mouth, describing the functions of incisors, canines, premolars, and molars in processing food.

05:01

🦷 Unique Dental Characteristics of Primates

The second paragraph delves into the unique dental characteristics found in various primates. It describes the primitive 2/1/3/3 dental formula and the derived 2/1/2/3 formula, noting that most primates fall into these categories. The paragraph also discusses exceptions, such as the tooth comb found in prosimians, which aids in grooming and provides a platform for chewing. The description of the lemur's jaw in side view illustrates the tooth comb and the dental formula. Additionally, the paragraph addresses the presence of diastema in apes and some monkeys, which accommodates their large canines. These canines are linked to both dietary and social behaviors, with examples given, such as the baboon's large canines for tearing meat and potential social display.

Keywords

💡Dentition

Dentition refers to the complete set of teeth in a person or animal. In the context of the video, it highlights the variety and generalization of primate teeth that allow for a diverse diet. The script discusses how primates' dentition, with its generalized form, is an adaptation to the arboreal environment where a wide range of plant foods are consumed at different times of the year.

💡Diet

Diet in the video script refers to the types of food that primates consume. It is central to understanding the relationship between primates' dentition and their ability to eat a variety of plant and animal matter. The script emphasizes that primates exhibit dietary plasticity, being omnivores that can eat both animals and plants, and that their teeth are adapted to process different kinds of food.

💡Arboreal Environment

An arboreal environment is one that is characterized by trees and a life adapted to living in trees. The script mentions this as the habitat where primates primarily live and forage for food, emphasizing the importance of having a dentition that can adapt to the seasonal availability of plant foods.

💡Dietary Plasticity

Dietary plasticity is the ability of an organism to consume a wide variety of foods. The script uses this term to describe how most primates, including humans, are omnivores with the capacity to eat both plant and animal matter, which is facilitated by their generalized dentition.

💡Omnivores

Omnivores are organisms that eat both plant and animal matter. The script explains that many primates, including humans, are omnivores, which is why they require a diverse set of teeth to process different types of food, from fruits to leaves and even meat.

💡Dental Formula

Dental formula is a method used by biologists to describe the arrangement and number of teeth in the mouth of a particular creature. The script explains how primates have two different dental formulas, 2/1/3/3 and 2/1/2/3, which are indicative of their evolutionary lineage and dietary habits.

💡Incisors

Incisors are the front teeth used for cutting and biting off food. The script describes how in primates, there are two incisors on each side of the upper and lower jaws, which are adapted for nipping or biting off chunks of food.

💡Canines

Canines are the pointed teeth located next to the incisors, used for tearing food. The script mentions that there is one canine tooth in each quadrant of the primate mouth, which plays a crucial role in the primate's ability to process food.

💡Premolars

Premolars are the teeth located behind the canines and are used for tearing and shredding food. The script explains that there are two premolars in the derived dental formula and three in the primitive formula of primates, indicating differences in their diet and evolutionary adaptations.

💡Molars

Molars are the large, flat teeth at the back of the mouth used for grinding food. The script describes how primates have three molars in each quadrant of the mouth, which are essential for processing the diverse plant foods that make up their diet.

💡Prosimians

Prosimians are a group of primates that are considered more primitive, including lemurs, pottos, and other similar creatures. The script mentions that prosimians have the primitive dental formula of 2/1/3/3 and some, like lemurs, have a tooth comb for grooming and feeding.

💡Diastema

Diastema refers to the gaps between teeth, particularly the large spaces adjacent to the canines in some primates. The script explains that apes and some monkeys have diastema to accommodate their large canines, which is an adaptation related to their diet and social behavior.

Highlights

Primates have a generalized dentition that allows for a wide variety of food consumption.

The arboreal environment necessitates eating plant foods at different times of the year due to seasonal availability.

A diverse diet is essential for primates, relying on a range of ripe plants throughout the year.

Primates exhibit high dietary plasticity, with many being omnivores consuming both animal and plant matter.

Different types of fruit and leaves require various chewing techniques, highlighting the adaptability of primate dentition.

Biologists use dental formula to describe the dentition of creatures, dividing the mouth into quadrants for analysis.

Primates have two dental formulas: 2/1/3/3 (primitive) and 2/1/2/3 (derived), with differences in premolar count.

The primitive dental formula 2/1/3/3 is found in New World monkeys and prosimians.

The derived dental formula 2/1/2/3 is present in Old World monkeys, apes, and humans.

Each tooth type in primates has a specific function: incisors for snipping, canines and premolars for tearing, and molars for crushing and grinding.

Prosimians possess a unique tooth comb, which aids in grooming and provides a platform for chewing.

Apes and some monkeys have large gaps called diastema to accommodate their oversized canines.

Large canines in primates are an adaptation for social behavior, diet, and defense mechanisms.

Baboons, for example, have large canines for tearing meat and social dominance.

The dental formula and tooth types are crucial for understanding the dietary habits and adaptations of primates.

Variations in primate dentition are often related to specific ecological niches and evolutionary pressures.

The combination of primate teeth allows for efficient processing of a diverse range of food sources.

Transcripts

PROFESSOR: In this segment, we are

going to talk about primates' teeth and diet.

Primates have a very generalized dentition.

This enables us to eat a wide variety of things.

This is a useful adaptation in the arboreal environment,

because we eat primarily plant foods.

And plants are suitable for eating

at different times of the year.

If you think of a tree with fruit on it,

well, that fruit is typically ripe in only

a particular season.

We can't rely on just one kind of plant,

or even just a handful of plants,

to get food 365 days a year.

So we have to eat a wide variety of things

that are ripe at different times of the year.

Having a wide variety of teeth gives us

a Swiss Army mouth that makes it possible for us to do that.

Most primates exhibit a high degree of dietary plasticity.

A lot of primates are omnivores.

People are omnivores.

We eat both animals and plants.

Some monkeys eat primarily fruit,

but they may eat a couple hundred different kinds

of fruit.

And if you just go to the produce department

at the supermarket, you see that there

is a lot of different fruit that comes in different shapes

and sizes and consistencies that requires

different ways to chew it and different ways to prepare it.

So plant matter is variable, as anything else.

Some monkeys eat leaves.

But there are different kinds of leaves that require

different amounts of chewing.

So we have in our head teeth that make it possible

for us to process a wide variety of different kinds

of foodstuff, even if we are focused

on one general category, like leaves or fruit.

When biologists look at the dentition

of a particular creature, they are able to--

dental formula is a method that biologists

use to describe the dentition of any particular creature.

What you do is divide the mouth into quadrants.

So you have upper left, upper right, lower left, lower right.

And then you count and categorize

the teeth that are in one of those quadrants of the mouth.

Primates have two different dental formula.

The two general formula that we see are 2/1/3/3 and 2/1/2/3.

2/1/3/3 is the primitive formula.

This is found in modern New World monkeys,

meaning monkeys in the Americas, and prosimians,

like lemurs, pottos, and other rosimians

that live in Africa and Asia.

2/1/2/3 is the derived or specialized dental formula,

and this is present in Old World monkeys--

monkeys that live in Africa and Asia across the sea--

all apes and us.

We'll talk about what platyrrhines and catarrhines

are in our primate evolution lecture more specifically.

So hold off on that for a second.

What do these numbers actually mean?

Well, let's look at the next slide, and I'll explain that.

This is a picture of the dentition of a gorilla.

On the left, we have the top teeth.

On the right, we have the bottom teeth.

Let's look at the picture on the left, the top teeth,

and divide that in half.

That gives us one quadrant of the overall mouth.

If we start at the midline, we see

two teeth that look similar.

These are flat and are used for nipping or biting off chunks.

These are the incisors.

So we have two incisors.

Next, we have the big pointy one.

That's the canine tooth.

There's just one of those.

Behind those, we have one, two premolars.

These are teeth that have two large cusps on them that

are right behind the canine.

And then behind that, we have one, two, three molars.

These are the flat ones that we use to grind.

Each of these teeth are used for different purposes.

The incisors snip or bite off chunks.

The canines and the premolars tear.

The molars crush and grind.

And because different foods that we eat

have to be eaten in a different way,

depending on their shape and density and consistency,

then we use different tools in our mouth

to process different foods in different ways,

so that we can eat it and get nutrition.

So we have two incisors, one canine, two premolars,

and three molars.

That's two, one, two, three.

If we showed a picture of a prosimian,

we would see that there is an extra premolar there.

That would give us three premolars for two, one, three,

three.

And I'll show you a slide about that in just a second.

The 2/1/3/3 primitive dental formula and the 2/1/2/3 derived

dental formula are the general trends that we see in primates.

Most primates fall into one of those two categories.

But there are others that have unique dentition that

are related to their particular circumstances.

And we'll look at some examples here.

Some primates have a tooth comb or dental comb,

where the front six teeth of their jaw on their lower

dentition project forward at a 90 degree angle

from the other teeth.

The only primates that today have a tooth comb

are prosimians.

So if you go to Madagascar and you see the ringtail lemurs

running around, those guys and all other prosimians

have this particular feature.

It helps them groom.

It also provides a platform for them to chew and grind.

This is a side view of the jaw of a lemur.

And you can see the tooth comb projecting forward.

This consists of both incisors and the canine.

So the two and the one in the dental formula

on either side of the jaw project forward

in this fashion.

If you look behind that, you see one, two, three premolars--

those first three teeth immediately

to the left of the tooth comb--

and one, two, three molars.

That's because prosimians have the primitive 2/1/2/3 dental

formula.

Apes and some monkeys have a unique characteristic

in their dentition.

They have large gaps called diastema

adjacent to their canines.

And this is because many apes and some monkeys

have really, really big canines.

This is on the left a picture of a chimp jaw.

On the right, that's the picture of a human jaw.

And you can see that canine on the chimp jaw

is much, much larger than the canine on the human jaw.

Well, because these teeth are so much bigger,

there has to be space to accommodate them

in the distribution of the teeth in the jaw,

so that the animal can open and close its mouth.

This gap, this diastema, makes it possible for the animal

to open and close its mouth and accommodate these very, very

large canines.

You're probably wondering, well, why

do they have big canines to begin with?

This is part of an adaptation related

to either their social behavior or their diet

in which large canines are adaptive.

This is a picture of a baboon.

You can see the massive canines that this creature has.

Why do baboons have such big fangs?

For a couple of reasons.

First, they're omnivores.

They eat meat, and they use these large canines

to tear chunks of meat off so that they can consume it,

much like a big cat has large canines.

They have them for the same reason,

so that they can consume animal meat.

There are social reasons that many primates

have large canines as well.

And these can be related to competition between males,

or in the baboons' case, defense.

We'll talk more about that in the primate behavior lecture

that is posted in this module.

So we'll leave that for then.

But suffice it to say, if an animal has these very large

canines, there has to be an accommodation for those

in the tooth spacing.

And you can see in the picture the large diastema

where these canines nest so that the animal can open and close

its mouth.