https://zh.wikipedia.org/wiki/%E6%96%B0%E7%94%9F%E4%BB%A3
新生代（Cenozoic） 是地球地質歷史上顯生宙的第三個、也是最晚的一個代，也是目前最年輕的一個地質時代，從6600萬年前白堊紀—古近紀滅絕事件開始一直持續至今。新生代下分三個紀（古近紀、新近紀、第四紀，前兩者曾被合稱第三紀），共七個世。
新生代是哺乳動物繁榮並占據各個生態圈的優勢生態位的時期，因此也稱「哺乳動物時代」。除此之外，鳥類、有鱗爬行類、滑體兩棲類、輻鰭魚和昆蟲也有很大發展，被子植物徹底成為優勢陸生植物，使得裸子植物和蕨類植物等逐漸衰落被邊緣化。
在新生代第四代晚期的全新世，屬於靈長目哺乳動物的智人通過新石器革命形成以農業為基礎的定居文明，並在之後的一萬年間通過技術的不斷進步成為地球有史以來唯一能夠大規模改變地表生態環境並離開大氣層、登陸其它天體並嘗試探索宇宙的物種。
https://zh.wikipedia.org/wiki/%E4%B8%AD%E7%94%9F%E4%BB%A3
中生代（Mesozoic）是地球地質歷史上顯生宙的三個地質時代之一，介於古生代與新生代之間，分為三疊紀、侏羅紀和白堊紀三個紀。由於這段時期是蜥形綱徹底擊敗合弓綱成為食物鏈上層生態位的優勢陸生動物、並壓倒各種兩棲類、魚類和頭足類成為優勢水生動物的時期，因此又稱為「爬行動物時代」；而因為三疊紀末期滅絕事件後恐龍迅速崛起成為之後1.5億年之間的優勢動物，侏羅紀和白堊紀也可稱為恐龍時代。
中生代也是板塊、氣候、生物演化改變極大的時代。在中生代開始時，各大陸連接為一塊超大陸－盤古大陸。盤古大陸後來分裂成南北兩片，北部大陸進一步分為北美和歐亞大陸，南部大陸分裂為南美、非洲、印度與馬達加斯加、澳洲和南極洲，只有澳洲沒有和南極洲完全分裂。中生代的氣候非常溫暖，對動物的演化產生影響。
https://zh.wikipedia.org/wiki/%E5%8F%A4%E7%94%9F%E4%BB%A3
古生代（Paleozoic，符號PZ）是地球地質歷史中顯生宙的第一個代，開始於同位素年齡5.42億年前（542±0.3 Ma），結束於2.51億年前（251±0.4 Ma），上承元古宙的新元古代，下啟中生代。古生代分為寒武紀、奧陶紀、志留紀、泥盆紀、石炭紀和二疊紀六個紀，其中寒武紀、奧陶紀又合稱早古生代，志留紀、泥盆紀合稱中古生代，石炭紀、二疊紀合稱晚古生代。
古生代是最早大規模出現史前動物化石的地質時期，是生物演化史（特別是動植物演化史）上的重要時期。古生代始於埃迪卡拉紀末大滅絕，隨後通過早期的寒武紀大爆發和之後的奧陶紀大輻射產生了幾乎所有現生動物的門和綱。這些早期動物的活動範圍只限於海洋，但在奧陶紀晚期和志留紀，有胚植物從淡水綠藻中演化出來並隨著真菌一起向乾燥陸地進發，除了通過固碳光合作用大大提高了大氣中的氧氣濃度外，其根系對地表岩石的侵蝕作用最終形成了土壤，為日後陸地生態系統的發展奠定了基礎。節肢動物（多足綱、蛛形綱和六足綱）率先登陸並在志留紀晚期成為徹底的陸生動物，隨後腹足類軟體動物和四足類脊椎動物（兩棲類）也在石炭紀先後登陸。在古生代後期，能夠離開水體繁衍的羊膜動物出現，並很快分化出合弓綱和蜥形綱兩大演化支。古生代終結於因西伯利亞暗色岩超級火山噴發引起的二疊紀末滅絕事件，是迄今所知最大的一次生物集群滅絕。
https://zh.wikipedia.org/zh-tw/%E6%98%BE%E7%94%9F%E5%AE%99
https://zh.wikipedia.org/wiki/%E5%9C%B0%E8%B4%A8%E5%B9%B4%E4%BB%A3
顯生宙（英語：Phanerozoic），或稱顯生元、顯生代，是地球地質歷史上最晚的一個宙，上承元古宙。顯生宙從5.41億年前延續至今，下分為古生代、中生代和新生代三個代，共十個紀。
顯生宙是複雜多細胞生物（特別是有主動移動性的動物和創造了地表土壤圈的植物）大量出現並多樣化的地質時期，特別是礦化組織的演化開始在地層中留下實體化石，使得後世人類研究史前生物變得有跡可循，以至於很長一段時間古生物學界曾一致認為生命史僅始於顯生宙，因而得名。
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| 中生代 （2.52億至6600萬年前） |
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| 新生代 （6600萬年前至今） |
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As an AI language model, I don't have access to real-time data or the ability to conduct original research. My responses are based on the information available up to my last training cut-off in January 2022.
Estimating the number of individuals who left Africa 60,000 to 90,000 years ago involves a degree of uncertainty, and there isn't a single consensus estimate among researchers. However, some genetic studies and population models have suggested that the number of individuals who migrated out of Africa during this time period could have been in the range of a few thousand to tens of thousands.
One influential study published in 2016, which analyzed genomic data from modern human populations, estimated that the ancestral population that migrated out of Africa may have consisted of around 1,000 to 5,000 individuals. However, it's important to note that this is just one estimate among many and that different studies may produce different results.
Overall, while we can make informed estimates based on genetic data, archaeological evidence, and computational models, the exact number of individuals who left Africa during this time period remains uncertain and subject to ongoing research and debate.
意思是說，五千人離開非洲，五千人滅共足已，
Estimating the precise number of individuals who left Africa during the period of 60,000 to 90,000 years ago is challenging due to limited archaeological evidence and the lack of written records from that time period. However, scientists have employed various methods to make informed estimates.
Genetic Studies: Genetic studies, particularly those focused on analyzing the DNA of modern human populations, have provided valuable insights into human migration patterns. By studying genetic diversity and using techniques such as molecular clock analysis, researchers have attempted to estimate the size of ancestral populations and the number of individuals who migrated out of Africa. However, these estimates can be imprecise and subject to certain assumptions.
Simulation Models: Computational models and simulations based on archaeological and genetic data can be used to simulate different migration scenarios and estimate population sizes. These models incorporate factors such as demographic trends, environmental conditions, and genetic data to generate estimates of past population sizes and migration patterns.
Archaeological Evidence: Archaeological evidence, such as ancient tools, artifacts, and fossil remains, can provide clues about past human populations and their movements. By studying the distribution of archaeological sites and artifacts, researchers can infer patterns of human migration and settlement. However, interpreting archaeological evidence can be challenging, and it may not always provide direct information about population sizes.
While these methods can provide valuable insights, it's important to recognize that estimating past population sizes and migration events involves uncertainties and limitations. Different studies may produce varying estimates, and our understanding of human migration history continues to evolve as new evidence and analytical techniques emerge. Therefore, any estimates of the number of people who left Africa 60,000 to 90,000 years ago should be interpreted with caution and viewed as approximate rather than definitive figures.
The migration of early human ancestors out of Africa was likely prompted by a combination of environmental, climatic, and demographic factors. Here are some key factors that may have played a role:
Climate Change: Changes in climate, particularly fluctuations in temperature and rainfall patterns, may have altered the availability of resources such as food and water. This could have created pressures for human ancestors to seek new habitats.
Population Pressure: As human populations grew in Africa, competition for resources may have intensified, leading groups to explore new territories in search of food and space.
Innovations in Tool Making and Hunting: Advances in tool-making and hunting techniques might have allowed early humans to exploit new environments more effectively, encouraging them to venture beyond their traditional territories.
Curiosity and Exploration: Humans, like many other species, have a natural curiosity and tendency to explore new environments. This innate curiosity could have driven early human ancestors to venture into new territories.
Natural Disasters: Catastrophic events such as droughts, floods, or volcanic eruptions could have disrupted local ecosystems and forced populations to migrate in search of more hospitable conditions.
Social or Cultural Reasons: Changes in social dynamics or cultural practices within early human communities may have also played a role in motivating migration, such as the desire to establish new social networks or exchange ideas with distant groups.
It's important to note that the exact reasons for human migration out of Africa are still subject to ongoing research and debate among scientists, and it's likely that multiple factors interacted to drive this complex process.