Not all humans are the same. There are differences, and different factors are determining those differences. Humans have different facial expressions and all of this is dependent on their genetics and their environmental factors. Most probably, the people belonging to the colder areas have thin and small lips, which help them in retaining their body heat. Similarly, black people have big thick lips.
Traits Of European People
European people have this thin lips trait in their genes and these genes started developing in the ice age when there was too cold and their lips started to help them in retaining their body temperature for their survival. These types of lips started developing out of their behaviors and habits in cold temperatures.
In winter and colder climates, when people clenched tight their mouths to maintain the temperature, they kept both their lips tight inwards their mouth and this became their habit over time. As the temperature starts to fall, more they kept their lips tighter, which eventually made their lips look thin and small. This practice was common in early white people because they had no way of maintaining normal body temperatures and surviving too much cold weather.
Due to the continuous habit of clenching lips, white people have thin lips as tightening the lips so much refrained them from accumulating fat. Even the fatty tissues present in the early people lips started dying, and soon almost everyone, regardless of being male or female, had the same size and type of lips. With time, thin lips started to become a genetic part of white people and this is the reason why people even now in Europe are born with small thin lips.
This issue has long been a part of debate now that what makes some people’s lips look bigger while in some ethnicities the lips are smaller and thin. The answer to this question is very simple: genetic codes in different people and ethnic groups are different. This difference develops over time with changing environmental factors and surroundings. However, the trends have been changed now for some people as they can have their type of “fuller lips” undergoing lip filler surgeries but white people have thin lips as it is in their genes.
Another cause is believed around the globe and is hopefully correct that ethnic groups and people having thin lips belong to the group of ancestors who headed north and belonged there and had spread later on. Science has already researched that we humans were chimpanzees, so these people with thinner lips are those of the remaining people, also referred to as muzzles who were previously the Chimpanzees.
The same happens when talking about Africans. As Africans have big fuller lips, this is for their genes have it. Black people belong to warmer climates. The hot temperatures molded their lower facial shape, and they had fuller big lips. As big lips are researched to have better heat dispersal.
However, considering only environmental factors shaping humans’ facial expressions would be unfair. Sexual selection and its impact cannot be ignored in this aspect.
In cold climates, people also appeal to their mates for breath and this becomes one of the reasons for thin and small lips. If we study history, whites were the people having the highest survival rate even living in extremely cold climates. Moreover, these people had had reproductive success.
The above stated are the basic scientific reasons for thin lips. However, there can be several other reasons too which apply equally to all ethnic groups of people:
1- Less Collagen Production
Collagen levels in your body are important to keep your skintight and fewer levels of collagen is regarded as one of the reasons for thin lips in people. Other than the genetic reasons, this can be a reason as well. Collagen is naturally developed in the human body and its development decreases with the passage of age.
2- Vitamin Deficiency
Vitamin B deficiency in the body can cause your lips to thin over time. You need to take a good healthy diet to maintain overall skincare, including your lips.
3- Extreme Weather
Extreme weather conditions like too cold or too much sun exposure can make your lips look thin. The same thing happens with white people due to cold temperatures. You need to take care of your lips from direct exposure to the sun so that they may remain thick and they do not lose their fatty tissues.