Sled Dog Hero Balto: A Good Dog with Great Genes

In 1925, a male sled dog named Balto led a 13-dog team through an extreme snowstorm during the final part of a 1,088-kilometer trip. The trip brought lifesaving medicine to the Alaskan city of Nome during an outbreak of the disease diphtheria.

Sled dogs pull sleds, which are small vehicles with a flat bottom that are used for moving over snow or ice.

Balto was celebrated¹ as a hero. He became the subject of books and movies. His preserved body still stands at the Cleveland Museum of Natural History in the state of Ohio.

Recently, scientists took DNA² from Balto's preserved body and studied it as part of a large project called Zoonomia. The massive study compares genetic³ information in different animals and humans.

Balto's genome, the scientists found, had certain genes⁴ that may have helped the dog deal with the extreme Alaskan environment and make it through the difficult trip.

Balto belonged to a population of working sled dogs in Alaska. The population was found to have greater genetic diversity and genetic health than modern dogs.

Diphtheria is a serious and sometimes deadly bacterial⁵ infection. When it spread among Nome's people, its port was blocked by ice. Sled dogs were the only way to get the important medicine to the city.

Balto was one of 150 dogs that pulled sleds for parts of the 127-hour trip. During the trip, temperatures reached minus-45 degrees Celsius⁶.

The researchers examined Balto's genome as a part of a dataset of 682 genomes from modern dogs and their animal ancestors, the wolf. The research also included the genes of 240 mammals and genes from humans.

Balto's genome showed lower rates of inbreeding than almost all modern dog breeds. Inbreeding is when animals are born from closely related parents. His genome also showed a lower rate of rare and possibly damaging genetic differences.

Balto was found to share ancestry⁷ with breeds like modern Siberian huskies and Alaskan sled dogs. He also was found to share ancestry with Greenland sled dogs, Vietnamese village dogs and Tibetan mastiffs. There was little evidence of wolf ancestry.

Born in 1919, Balto was part of a population of sled dogs imported from Siberia, known as Siberian huskies. The study showed that these dogs greatly differed from modern Siberian huskies, however. Balto had a body built for strength and not speed, which his breeder did not necessarily like. The breeder had the dog's sex organs removed so he could not be used to produce young dogs.

Balto's life after that Alaska trip was a difficult one. He was mistreated by humans. Thankfully, a visiting Cleveland businessman saw Balto's mistreatment and bought the dogs for $1,500. The money was raised by the local community in Cleveland.

In 1927, Balto and his dog co-runners Alaska Slim, Billy, Fox, Old Moctoc, Sye, and Tillie were celebrated in Cleveland on their arrival. They then spent the rest of their lives cared for at the local Brookside Zoo. Balto died of natural causes in 1933.

Kathleen Morrill is the study's co-writer and a scientist at the biotech company Colossal⁸ Biosciences. She said of Balto's heroic mission, "These specialized⁹ dogs don't know that what they do has such gravity in people's lives."

She added that the sled dogs' genetic makeup¹⁰ "set them up to be the best animals for the job."

Words in This Story

preserve v. to keep (something) in its original state or in good condition

diversity – n. the quality or state of having many different forms, types, ideas, etc.

mammal – n. a type of animal that feeds milk to its young and that usually has hair or fur covering most of its skin

gravity – n. extreme importance; a very serious quality or condition

1 celebrated   

adj.有名的，声誉卓著的

参考例句：

• He was soon one of the most celebrated young painters in England.不久他就成了英格兰最负盛名的年轻画家之一。
• The celebrated violinist was mobbed by the audience.观众团团围住了这位著名的小提琴演奏家。

2 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

3 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

4 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

5 bacterial   

a.细菌的

参考例句：

• Bacterial reproduction is accelerated in weightless space. 在失重的空间，细菌繁殖加快了。
• Brain lesions can be caused by bacterial infections. 大脑损伤可能由细菌感染引起。

6 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

7 ancestry   

n.祖先，家世

参考例句：

• Their ancestry settled the land in 1856.他们的祖辈1856年在这块土地上定居下来。
• He is an American of French ancestry.他是法国血统的美国人。

8 colossal   

adj.异常的，庞大的

参考例句：

• There has been a colossal waste of public money.一直存在巨大的公款浪费。
• Some of the tall buildings in that city are colossal.那座城市里的一些高层建筑很庞大。

9 specialized   

adj.专门的，专业化的

参考例句：

• There are many specialized agencies in the United Nations.联合国有许多专门机构。
• These tools are very specialized.这些是专用工具。

10 makeup   

n.组织；性格；化装品

参考例句：

• Those who failed the exam take a makeup exam.这次考试不及格的人必须参加补考。
• Do you think her beauty could makeup for her stupidity?你认为她的美丽能弥补她的愚蠢吗？