Your daily life is probably shaped by these 12 people—do you know their names?

Ever wonder who came up with the idea of a metal staircase on high-rises to escape fires? What about the citrus hybrid fruit known as tangelo—what is that all about? And the LEGO blocks that have captivated children for decades, where did that come from?

Here are 12 people whose inventions changed our history.

1). Anna Connelly (birth and death dates unknown)

In 1887 American-born Connelly patented an idea that would save countless lives: the metal fire escape. During the late 19th century, many fires in multistory buildings forced residents to jump to their deaths. Connelly designed a steel staircase that could be attached to the outside of a building. People could escape down, and firefighters could go up. Fire escapes changed the way buildings were constructed in the early 1900s as cities increasingly included the escapes in their building codes.

2). Ammar ibn Ali Al-Mawsili (d. circa 1010)

A 10th-century eye doctor is responsible for the invention of the hypodermic syringe. Long before sophisticated ophthalmological techniques, Al-Mawsili developed a method for removing cataracts, a leading cause of blindness. In those days, people who went blind often died shortly after. The groundbreaking syringe was a glass tube that used suction to perform the task. Al-Mawsili was born in what is now Iraq but moved to Egypt as a young man. The technique he developed roughly 1,000 years ago still influences how cataracts are removed today.

3). Chief Seattle (1780–1866)

Chief Seattle and his deeds inspired Washington State’s capital city, then a nameless settlement. Chief of the native Duwamish and Suquamish tribes around Puget Sound, he became known as both a warrior and a diplomat. He built his oratorical skills as he forged cooperation among his own tribes. He wanted to work and live in peace with everyone, including the European settlers arriving in the Pacific Northwest. Chief Seattle did so much to pave the way toward cooperation between the tribes and the newcomers that the early white settlers, led by David Swinson “Doc” Maynard, named their village Seattle. Though he was a peacemaker, the chief had grave concerns about the impact of the influx of settlers on the local populace and on the environment. In 1855 he gave an inspiring speech to the governor of the Washington Territory (now Seattle), which was later transcribed and printed. It turned Chief Seattle into a folk icon.

He became a prominent figure in conversations about the treatment of native people, and he promoted the idea that humans should see themselves as part of nature, not tamers of it.

4). Ellen H. Swallow Richards (1842–1911)

This chemist broke barriers in American science and pioneered sanitary engineering in venues ranging from state to kitchen. After earning a bachelor’s degree from Vassar College in 1870, Richards was accepted as a “special student” at all-male MIT, becoming the first woman in the United States to attend a science school. Her bachelor’s degree from MIT was matched by a master’s from Vassar the same year.

Richards went on to promote the education of women in science and also to conduct a huge survey of water quality in Massachusetts, an endeavor that led to the first state water-quality standards in the nation. She applied the same scientific rigor to the household, writing The Chemistry of Cooking and Cleaning, setting up model kitchens, and establishing the field of home economics.

5). Gregor Mendel (1822–1884)

Mendel was a 19th-century botanist and cleric who discovered the key to plant heredity. In the mid- 1800s, he experimented with pea plants to determine how physical traits pass from one generation to the next. The experiments established the basic rules needed to create a hybrid—a cross between two or more parent plants that creates a new variety with desired characteristics. Tangelos (tangerine and pomelo or grapefruit) and tayberries (blackberry and red raspberry) are delicious examples of hybrids.

6). Jane Jacobs (1916–2006)

Jacobs was not a formally trained urban planner and didn’t have a college degree, but her grounded, intelligent views on community planning changed the way Americans thought about cities. In her 1961 book, Death and Life of Great American Cities, Jacobs advocated pedestrian-friendly, human-scale neighborhoods featuring short city blocks and mixed-use buildings that encouraged resident interaction. She also staunchly opposed high-rise developments and expressways that bisected neighborhoods, arguing that they disrupted a city’s urban fabric and damaged its social cohesion.

7). Louis Pasteur (1822–1895)

A groundbreaking French chemist and microbiologist, Pasteur is responsible for major discoveries that led to the germ theory of disease. He’s probably best known for developing the process of pasteurization in the 1860s, in which foods are subjected to high heat to kill harmful microorganisms. Pasteurization was first applied to wine and later to milk and beer. Many of our most common perishable foods, such as fruit juices and dairy products, are now required by law to undergo pasteurization or to be produced using pasteurized ingredients.

8). Marcus Virgilius Eurysaces (circa 50–20 B.C.)

This freed slave of Greek background is credited with inventing the first labor-saving device for bakers: a mechanical dough mixer. Eurysaces attached horses or donkeys to mixing paddles inside a large stone basin. As the animals circled around the platform, the paddles mixed and kneaded the bread dough.

9). Marie Curie (1867–1934)

Born Maria Sklodowska, she was not allowed to go to Warsaw’s male-only university in the late 1800s, so she studied math and science on her own, working as a governess to support herself. She moved to Paris and excelled at the Sorbonne, where she received degrees in physics and mathematics and met her physicist husband, Pierre Curie. Together they discovered polonium and radium. Marie came to understand the origin of x-rays and coined the term “radioactivity.” In 1903 she was the first woman to win the Nobel Prize in physics. During World War I, she pioneered portable x-ray machines that were nicknamed “Little Curies.” Sadly, in 1934 Marie Curie died from long-term radiation exposure.

10). Margaret Knight (1838–1914)

Knight was born in Maine in 1838, had scant schooling, and never traveled far from home. Yet she became one of our nation’s most prolific inventors. Before electricity, mills making textiles, shoes, and other products were powered by waterwheels turned by rivers—plentiful in New England. Like many other young women, Knight became a factory girl.

Reportedly, she began inventing at the age of 12 after witnessing an accident at her textile mill. The device she created stopped machines if objects were caught in them. Her invention gained wide acceptance, but she didn’t receive a patent. Years later, working at a paper-bag factory, she invented the first machine to make flat-bottomed bags—the kind we still use today. When a fellow machinist tried to patent it himself, she took him to court—and won. Knight earned dozens more patents during her lifetime, including a machine to cut leather soles, a sewing-machine reel, and a rotary engine.

11). Ole Kirk Christiansen (1891–1958)

The youngest of 10 children, this Danish carpenter was born in 1891. By 1932, with the Depression in full swing in Denmark, he was a widowed father of four and the owner of a small woodworking shop that made ladders, stools—and toys. His small painted birch-wood bricks were his most popular offerings and inspired Christiansen to focus on making more. He renamed the company LEGO, after the Danish words leg and godt, literally “play well.” LEGO blocks with their patented interlocking tubes were introduced in 1958, the same year Christiansen died. The LEGO company is still run by the Christiansen family.

12). Ray Kroc (1902–1984)

As the founder of McDonald’s restaurants, Kroc changed the way Americans eat. In 1954, Kroc was selling industrial mixers and visited the California restaurant of two of his best customers, Maurice and Richard McDonald. Kroc was impressed by the assembly-line methods the brothers used to make their hamburgers, cheeseburgers, french fries, and milkshakes.

Kroc, an Illinois native, talked the McDonalds into allowing him to create a group of drive-in hamburger restaurants using their methods and name. The first of his restaurants opened in Des Plaines, Illinois, on April 15, 1955. By 1960 there were 200. Today there are more than 36,000 McDonald’s in more than 100 countries worldwide, employing nearly 2,000,000 people.