The Evolution of enjoying Ice Cream

Today, 65 percent of the global population is considered lactose intolerant. This means that have the inability to digest lactose which is a component of milk and some other dairy products. Those who are lactose intolerant lack an enzyme called lactase which is in their small intestine ( We all started drinking milk when we were just a couple hours old and yet now a huge portion of our population has difficulties digesting it.

Lactase is a protein that breaks down the lactose molecule into two. The gene that codes for lactase is carried by those who drank milk as a baby.  For those who can digest lactose, the gene continues to work even in adulthood which allows them to eat and drink dairy products without upsetting their stomachs. The gene may be turned off after they weaned off of milk as a child and then cannot properly digest products containing lactose in their adult years.

A team of German and British researchers decided that they were going to experiment with the mutation that keeps the lactase gene turned on in 2007. Their findings suggested that lactose intolerant began in 5000 BC even though they lived in a milk drinking society. There did not find a reason why the intolerant arose but since then it has spread to all areas of the world. Natural selection could have favored those who do carry the gene that can tolerate the lactose protein.


If it wasn’t for people 10,000 no one today would be able to enjoy ice cream that we all know and love or cheese. Way back then no one could digest this milk sugar, lactose. What they would do to be able to digest milk was fermenting the cow or camel milk to rid the sugar. The amount of tolerance one has to lactose is dependent on your ancestors. Those who are of African, Asia, or Mediterranean descent, cannot digest it at all.

Prevalence of lactose intolerance


Being lactose intolerant myself, I have always wondered why some people are and how I became lactose intolerant. When I was younger I drank milk with every meal until about 7th grade where I started to have symptoms. My dad and sister are both lactose intolerant so I figured it out pretty quickly. It was interesting to do this research and be able to answer some of the questions I have been wondering for the past 7-8 years. For those of you who can eat dairy without getting an upset stomach, I am jealous. Next time you are enjoying your ice cream cone on a hot summer day, think of us other people who can’t have that same delicious treat.




Hi, my names Stephanie Ryder and I am a junior at Keene State. I am majoring in Elementary Education and Math.

3 thoughts on “The Evolution of enjoying Ice Cream

  1. It is interesting to see how a mutation in a gene (or set of genes), that can confer survival advantages (like lactose tolerance) can spread fairly rapidly throughout populations. It seems unclear in your post whether you are indicating that adult lactose tolerance or lactose Intolerance
    is the more primitive condition? (that is, which came first?). Also, make sure that you get the spellings right for LACTASE – to indicate the enzyme (protein) that digests LACTOSE (the sugar in milk). I would love to see some other articles/research that you link to and write about on this.


  2. As a nutrition student, I am intrigued by food intolerances, allergies, and so on. The title of your blog post really caught my attention. I found this post to be very informative. It is very clear and easy to understand. I love how you used a map as an image in your post. It gives a great visual of the worldwide prevalence of lactose intolerance. Overall, great job!

    Liked by 1 person

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