Muscles in the back of a 10-week-old human embryo’s hand called dorsometacarpales (the two smallest horizontal muscles highlighted at center) will be lost or fuse with other muscles during development. Image: RUI DIOGO, NATALIA SIOMAVA AND YORICK GITTON

Scientists have released incredible images showing the complex muscle structure of unborn babies in the first trimester.

New technology which provides high-quality 3D images of the arm and leg muscles in embryos and foetuses led to the discovery that unborn babies develop extra muscles that disappear before birth.

"Super-humans"

For instance, babies at seven weeks’ gestation have about 30 muscles in their hands, while adults have 19. Many of the muscles are lost, and some fuse with others, adopting the adult arrangement by 13 weeks of gestation.

Dr Rui Diogo from Howard University, US,said: We are really losing things that will make super-humans.

"Super-humans would be keeping those muscles because you would be able to move all your digits, including your feet, as thumbs.

"We lost them because we do not need them."

Evolutionary relic?

Far from being a "blob of cells" as abortion advocates claim, unborn babies in the first trimester are highly developed.

According to the research, published in the journal Development, the extra muscles could be the oldest, albeit fleeting, remnants of evolution seen in humans yet. The extra hand muscles were lost in our adult ancestors around 250 million years ago (when reptiles transitioned into mammals) - but are present in many other limbed animals such as monkeys.

Keeping the muscles into adulthood would have allowed humans to move all of their digits - and feet - in a similar way to the thumb, according to the study’s lead author. "We have a lot of muscles going to the thumb, very precise thumb movements, but we lost a lot of muscles that are going to the other digits - in our evolution, we do not need them so much," Dr Rui Diogo from Howard University, US, told the BBC. 

Amazing techniques allowing window into womb

The biologists are planning more work looking at other parts of the human body in detail.

They have already studied the feet and know extra muscles develop and disappear there too while babies grow in the womb.

Monkeys and apes still have these muscles and use them to climb and manipulate objects with their feet.

The study could also build understanding of certain birth defects, which may be caused by the muscles persisting into adulthood. 

Dr Diogo added: "It used to be that we had more understanding of the early development of fishes, frogs, chicken and mice than in our own species.

"But these new techniques allow us to see human development in much greater detail."

 So it seems that unborn babies can give vital information about the development of humanity itself!