Судлаачид археологийн малтлагаар олдсон эртний хүний тархины эд эс ялзрахгүйгээр хадгалагдаж ирсэн химийн үндсэн шалтгааныг тогтоов.
Археологийн түүхийн туршид 4,400 гаруй хүний тархи ялзралд өртөлгүйгээр бүрэн бүтэн олдсон нь эрдэмтдийн дунд “тархи хадгалагдах парадокс” хэмээх тааврыг үүсгэжээ. Их Британийн Оксфордын их сургуулийн палеобиологич Александра Сэвиор тэргүүтэй судлаачдын баг энэхүү үзэгдлийг тайлбарлах зорилгоор зургаан сарын турш хулганы цогцос ашиглан туршилт явуулсан байна. Тэд цогцсыг чийгшил болон хүчилтөрөгчийн өөр өөр нөхцөлд булж, уургийн задралын явцыг өндөр нарийвчлалтай масс спектрометрийн аргаар шинжилжээ.
Туршилтын үр дүнд хүчилтөрөгч багатай, чийгтэй орчин нь тархины эд эсийн задралыг удаашруулж, улмаар уургийн бүтцийг бэхжүүлдэг болох нь тогтоогдсон байна. Хүчилтөрөгч ихтэй орчинд чөлөөт радикалууд нь уургийг хурдан задалдаг бол, чийгтэй бөгөөд хүчилтөрөгч багатай орчинд химийн урвал өөрчлөгдөж, уураг нь хоорондоо илүү бат бөх холбоо үүсгэдэг ажээ. Тархины бүтцэд агуулагдах металл, өөх тосны мембран болон амин хүчлүүд нь энэхүү хамгаалалтын бүрхүүлийг үүсгэхэд гол үүрэг гүйцэтгэдэг болохыг судалгаагаар илрүүлсэн байна.
Эрдэмтдийн тайлбарласнаар, гавлын яс нь гадны нөлөөлөл, шингэн болон хүчилтөрөгчийн урсгалыг хязгаарласнаар энэхүү хадгалагдах үйл явцад нэмэлт дэмжлэг үзүүлдэг байж болзошгүй юм. Мөн энэхүү судалгааны явцад олдсон уургийн задралын хэв шинж нь Альцгеймерийн өвчин зэрэг мэдрэлийн доройтлын өвчлөлийн үед ажиглагддаг өөрчлөлтүүдтэй төстэй байгаа нь анхаарал татаж байна.
Судлаачид энэхүү химийн үйл явц нь тархинаас бусад эрхтэн эсвэл өөр орчинд хэрхэн явагддаг болохыг нарийвчлан тодруулах шаардлагатай гэж үзэж байна. Энэхүү нээлт нь археологийн олдворуудын хадгалагдалтын талаарх өмнөх ойлголтыг өөрчилж, задралын явцыг илүү гүнзгий ойлгох боломжийг олгож байна. Одоогоор эрдэмтэд тархины эд эсийн энэхүү өвөрмөц хадгалагдалтын явц болон мэдрэлийн өвчлөлийн хооронд холбоо байгаа эсэхийг цаашид судлах шаардлагатай байгааг тэмдэглэжээ.
Дэлгэрэнгүйг эх сурвалжаас харах
↓Эх сурвалжийг нээх ↓
For decades, archaeologists have puzzled over a strange phenomenon: skeletons stripped bare by time, with only one soft and unlikely survivor remaining, the brain. Now, a team of researchers says it has finally uncovered the chemistry behind this mystery. It appears that the answer does not come from a rare preservation accident, but rather from the very process of decay itself.
The mystery, known as the brain preservation paradox, has challenged scientists for years. More than 4,400 preserved human brains have been documented across 12,000 years of archaeological history, according to earlier research by Alexandra Seviour, a doctoral researcher in paleobiology at the University of Oxford. The fact that brain tissue can survive while skin, muscles, and other organs disappear has long appeared to contradict the basic principles of decomposition.
What makes the discovery even more remarkable is where these preserved brains are often found. Around one third are discovered in waterlogged, oxygen-poor environments such as riverbeds, lake shores, flooded caves, and shipwrecks, places usually associated with decay rather than preservation.
A Six-Month Experiment Buried In The Dirt
To test their theory, the team behind the new study, published June 19 in the Journal of Proteome Research, buried mouse carcasses under four different combinations of water and oxygen conditions and monitored their decomposition over six months.
At specific intervals, including 24 hours, 72 hours, one week, six weeks, three months, and six months, the researchers examined the brains and analyzed them using high-resolution mass spectrometry to determine which proteins remained intact and which ones broke down.
“We were looking for which specific peptides survived and which vanished, and what chemical marks were left on the survivors,” Alexandra Seviour explained.
The researchers’ analysis generated more than 1.26 million protein decay patterns. At first, the decomposition process looked similar in all four burial conditions. But after a few weeks, oxygen levels began to make a major difference.
Environments with more oxygen caused the brain tissue to break down faster, while wet, oxygen-poor settings helped create tougher protein structures that could withstand decay. These structures may explain how some ancient brains have managed to survive for thousands of years.
Free Radicals Hold The Key
According to Seviour, the secret may come down to free radicals, unstable particles that can damage cells and proteins. When there is plenty of oxygen, these particles trigger reactions that quickly break down proteins and speed up decay. But in wet environments with very little oxygen, the process changes.
Instead of destroying the proteins completely, the reaction slows down. Some of the chemical compounds left behind can then attach to nearby proteins, creating tougher structures that are much harder to break apart.
The brain seems to be especially well suited for this unusual form of preservation. It contains metals that can fuel these reactions, fatty membranes where free radicals can build up, and certain amino acids that help trap them and create stronger protective bonds. The skull may also help by limiting the flow of fluids and oxygen compared with other parts of the body.
An Unexpected Link To Alzheimer’s Disease
Richard Evershed, an organic geochemist at the University of Bristol who was not involved in the study, described the research as a comprehensive analysis. He suggested that:
“Comparing more tissues — other organs and muscles — would be really useful to get an idea whether what was happening in the brain was special compared to what was happening elsewhere, and also to resolve questions regarding proteins preserved in other environments in archaeology such as pots or dental calculus.”
Seviour also explained that the molecular patterns found in these decay-resistant proteins look similar to those seen in neurodegenerative diseases such as Alzheimer’s disease. Scientists still need to study these similarities further to understand whether the two processes are truly connected.
Enjoyed this article? Subscribe to our free newsletter for engaging stories, exclusive content, and the latest news.
